Method and apparatus for discriminating and counting document

ABSTRACT

A currency counting and discrimination device for receiving a stack of currency bills, rapidly counting and discriminating the bills in the stack, and then re-stacking the bills. The device comprises an input receptacle for receiving a stack of currency bills to be discriminated, a discriminating unit for discriminating the denomination of the currency bills, and one or more output receptacles for receiving the currency bills after being discriminated by the discriminating unit. The device further comprises a transport mechanism for transporting the currency bills, one at a time, from the input receptacle past a sensor of the discriminating unit and to the one or more output receptacles. One or more counters keep track of the value of bills that are discriminated. Furthermore, means are provided for an operator of the device to indicate the value of any bills whose denomination are not determined by the discriminating unit; the bills whose denomination are not determined by the discriminating unit being termed no call bills. The value indicating means appropriately effects the one or more counters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending application Ser. No.08/573,392, filed on Dec. 15, 1995, now U.S. Pat. No. 5,790,697 entitled“Method Apparatus For Currency Discrimination And Counting.” ApplicationSer. No. 08/573,392 is a continuation-in-part of the following pendingU.S. patent applications:

Ser. No. 08/399,854 filed Mar. 7, 1995, and issued as U.S. Pat. No.5,875,259 on Feb. 23, 1999, for a “Method and Apparatus ForDiscriminating and Counting Documents”;

Ser. No. 08/394,752 filed Feb. 27, 1995, and issued as U.S. Pat. No.5,724,438 on Mar. 3, 1998, for a “Method of Generating Modified Patternsand Method and Apparatus for Using the Same in a Currency IdentificationSystem”;

Ser. No. 08/362,848 filed Dec. 22, 1994, and issued as U.S. Pat. No.5,870,487 on Feb. 9, 1999, for a “Method And Apparatus ForDiscriminating and Counting Documents”;

Ser. No. 08/340,031 filed Nov. 14, 1994, and issued as U.S. Pat. No.5,815,592 on Sep. 29, 1998, for a “Method And Apparatus ForDiscriminating and Counting Documents”;

Ser. No. 08/317,349 filed Oct. 4, 1994, and issued as U.S. Pat. No.5,640,463 on Jun. 17, 1997, for a “Method And Apparatus ForAuthenticating Documents Including Currency”;

Ser. No. 08/287,882 filed Aug. 9, 1994, and issued as U.S. Pat. No.5,652,802 on Jul. 29, 1997, for a “Method and Apparatus for DocumentIdentification”;

Ser. No. 08/243,807 filed May 16, 1994, and issued as U.S. Pat. No.5,633,949 on May 27, 1997, for “Method And Apparatus For CurrencyDiscrimination”; and

Ser. No. 08/226,660 filed Apr. 12, 1994, for “Method And Apparatus ForCurrency Discrimination”.

U.S. patent application Ser. No. 08/399,854 filed Mar. 7, 1995 andissued as U.S. Pat. No. 5,875,259 on Feb. 23, 1999, for a “Method andApparatus For Discriminating and Counting Documents” is acontinuation-in-part of pending U.S. patent applications Ser. No.08/394,752 filed Feb. 27, 1995 and issued as U.S. Pat. No. 5,724,438 onMar. 3, 1998, for a “Method of Generating Modified Patterns and Methodand Apparatus for Using the Same in a Currency Identification System,”Ser. No. 08/340,031, and issued as U.S. Pat. No. 5,815,592 on Sep. 29,1998and Ser. No. 08/287,882 and issued as U.S. Pat. No. 5,652,802 onJul. 29, 1997.

U.S. patent application Ser. No. 08/394,752 filed Feb. 27, 1995 andissued as U.S. Pat. No. 5,724,438 on Mar. 3, 1998, for a “Method ofGenerating Modified Patterns and Method and Apparatus for Using the Samein a Currency Identification System” is a continuation-in-part ofpending U.S. patent applications Ser. No. 08/340,031 and issued as U.S.Pat. No. 5,815,592 on Sep. 29, 1998, and Ser. No. 08/127,334 filed Sep.27, 1993, and issued as U.S. Pat. No. 5,467,405 on Nov. 14, 1995, for a“Method and Apparatus for Currency Discrimination and Counting.”

U.S. patent application Ser. No. 08/362,848 filed Dec. 22, 1994, andissued as U.S. Pat. No. 5,870,487 on Feb. 9, 1999, for a “Method AndApparatus For Discriminating and Counting Documents” is acontinuation-in-part of pending U.S. patent application Ser. No.08/340,031 and issued as U.S. Pat. No. 5,870,487 on Feb. 9, 1999.

U.S. patent application Ser. No. 08/340,031 filed Nov. 14, 1994, andissued as U.S. Pat. No. 5,815,592 on Sep. 29, 1998 for a “Method AndApparatus For Discriminating and Counting Documents” is acontinuation-in-part of pending U.S. patent applications Ser. No.08/243,807 and issued as U.S. Pat. No. 5,633,949 on May 27, 1997, andSer. No. 08/207,592 filed Mar. 8, 1994 and issued as U.S. Pat. No.5,467,406 on Nov. 14, 1995, for “Method and Apparatus for CurrencyDiscrimination”.

U.S. patent application Ser. No. 08/287,882 filed Aug. 9, 1994 andissued as U.S. Pat. No. 5,652,802 on Jul. 29, 1997, for a “Method andApparatus for Document Identification” is a continuation-in-part ofpending U.S. patent applications Ser. No. 08/207,592, and issued as U.S.Pat. No. 5,467,406 on Nov. 14, 1995, Ser. No. 08/219,093 filed on Mar.29, 1994, now abandoned, for a “Currency Discriminator andAuthenticator”, and Ser. No. 08/127,334 filed Sep. 27, 1993, and issuedas U.S. Pat. No. 5,467,405 on Nov. 14, 1995, for a “Method and Apparatusfor Currency Discrimination and Counting.”

U.S. patent application Ser. No. 08/243,807 filed May 16, 1994, andissued as U.S. Pat. No. 5,633,949 on May 27, 1997, for “Method AndApparatus For Currency Discrimination” is a continuation-in-part ofpending U.S. patent applications Ser. No. 08/219,093, now abandoned, andSer. No. 08/127,334 and issued as U.S. Pat. No. 5,467,405 on Nov. 14,1995.

U.S. patent application Ser. No. 08/226,660 filed Apr. 12, 1994, for“Method And Apparatus For Currency Discrimination” is acontinuation-in-part of pending U.S. patent application Ser. No.08/127,334 and issued as U.S. Pat. No. 5,467,405 on Nov. 14, 1995.

U.S. patent application Ser. No. 08/219,093 filed on Mar. 29, 1994, nowabandoned, for a “Currency Discriminator and Authenticator” is acontinuation-in-part of pending U.S. patent application Ser. No.08/127,334 and issued as U.S. Pat. No. 5,467,405 Nov. 14, 1995.

U.S. patent application Ser. No. 08/207,592 filed Mar. 8, 1994, andissued as U.S. Pat. No. 5,467,406 on Nov. 14 1995, for “Method andApparatus for Currency Discrimination” is a continuation-in-part ofpending U.S. patent application Ser. No. 08/127,334 and issued as U.S.Pat. No. 5,467,405 on Nov. 14, 1995.

U.S. patent application Ser. No. 08/127,334 filed Sep. 27, 1993, andissued as U.S. Patent No. 5,467,405 on Nov. 14 1995, for a “Method andApparatus for Currency Discrimination and Counting,” is a continuationof U.S. patent application Ser. No. 07/885,648, filed on May 19, 1992,and issued as U.S. Pat. No. 5,295,196 on Mar. 15, 1994, for a “Methodand Apparatus for Currency Discrimination and Counting,” which is acontinuation-in-part of abandoned U.S. patent application Ser. No.07/475,111, filed Feb. 5, 1990, for a “Method and Apparatus for CurrencyDiscrimination and Counting.”

FIELD OF THE INVENTION

The present invention relates, in general, to document identification.More specifically, the present invention relates to an apparatus andmethod for discriminating among a plurality of document types such ascurrency bills of different denominations and/or from differentcountries and authenticating the genuineness of the same.

BACKGROUND OF THE INVENTION

Machines that are currently available for simultaneous scanning andcounting of documents such as paper currency are relatively complex andcostly, and relatively large in size. The complexity of such machinescan also lead to excessive service and maintenance requirements. Thesedrawbacks have inhibited more widespread use of such machines,particularly in banks and other financial institutions where space islimited in areas where the machines are most needed, such as tellerareas. The above drawbacks are particularly difficult to overcome inmachines which offer much-needed features such as the ability to scanbills regardless of their orientation relative to the machine or to eachother, and the ability to authenticate genuineness and/or denominationof the bills.

A variety of techniques and apparatus have been used to satisfy therequirements of automated currency handling systems. At the lower end ofsophistication in this area of technology are systems capable ofhandling only a specific type of currency, such as a specific dollardenomination, while rejecting all other currency types. At the upper endare complex systems which are capable of identifying and discriminatingamong and automatically counting multiple currency denominations.

Currency discrimination systems typically employ either magnetic sensingor optical sensing for discriminating among different currencydenominations. Magnetic sensing is based on detecting the presence orabsence of magnetic ink in portions of the printed indicia on thecurrency by using magnetic sensors, usually ferrite core-based sensors,and using the detected magnetic signals, after undergoing analog ordigital processing, as the basis for currency discrimination. A varietyof currency characteristics can be measured using magnetic sensing.These include detection of patterns of changes in magnetic flux,patterns of vertical grid lines in the portrait area of bills, thepresence of a security thread, total amount of magnetizable material ofa bill, patterns from sensing the strength of magnetic fields along abill, and other patterns and counts from scanning different portions ofthe bill such as the area in which the denomination is written out.

The more commonly used optical sensing techniques, on the other hand,are based on detecting and analyzing variations in light reflectance ortransmissivity characteristics occurring when a currency bill isilluminated and scanned by a strip of focused light. The subsequentcurrency discrimination is based on the comparison of sensed opticalcharacteristics with prestored parameters for different currencydenominations, while accounting for adequate tolerances reflectingdifferences among individual bills of a given denomination. A variety ofcurrency characteristics can be measured using optical sensing. Theseinclude detection of a bill's density, color, length and thickness, thepresence of a security thread and holes, and other patterns ofreflectance and transmission. Color detection techniques may employcolor filters, colored lamps, and/or dichroic beamsplitters.

In addition to magnetic and optical sensing, other techniques ofdetecting characteristic information of currency include electricalconductivity sensing, capacitive sensing (such as for watermarks,security threads, thickness, and various dielectric properties) andmechanical sensing (such as for size, limpness, and thickness).

A major obstacle in implementing automated currency discriminationsystems is obtaining an optimum compromise between the criteria used toadequately define the characteristic pattern for a particular currencydenomination, the time required to analyze test data and compare it topredefined parameters in order to identify the currency bill underscrutiny, and the rate at which successive currency bills may bemechanically fed through and scanned. Even with the use ofmicroprocessors for processing the test data resulting from the scanningof a bill, a finite amount of time is required for acquiring samples andfor the process of comparing the test data to stored parameters toidentify the denomination of the bill.

Some of the currency scanning systems today scan for two or morecharacteristics of bills to discriminate among various denominations orto authenticate their genuineness. However, these systems do notefficiently utilize the information which is obtained. Rather, thesesystems generally conduct comparison based on the two or morecharacteristics independently of each other. As a result, the timerequired to make these comparisons is increased which in turn can reducethe operating speed of the entire scanning system.

Recent currency discriminating systems rely on comparisons between ascanned pattern obtained from a subject bill and sets of stored masterpatterns for the various denominations among which the system isdesigned to discriminate. As a result, the master patterns which arestored play an important role in a discrimination system's ability todiscriminate among bills of various denominations as well as betweengenuine bills and counterfeit bills. These master patterns have beengenerated by scanning bills of various denominations known to be genuineand storing the resulting patterns. However, a pattern generated byscanning a genuine bill of a given denomination can vary depending upona number of factors such as the condition of the bill, e.g., whether itis a crisp bill in new condition or a worn, flimsy bill, as well as yearin which the bill was printed, e.g., before or after security threadswere incorporated into bills of some denominations. Likewise, it hasbeen found that bills which have experienced a high degree of usage mayshrink, resulting in a reduction of the dimensions of such bills. Suchshrinkage may likewise result in variations in scanning patterns. As aresult, if, for example, a $20 master pattern is generated by scanning acrisp, genuine $20 bill, the discrimination system may reject anunacceptable number of genuine but worn $20 bills. Likewise, if a $20master pattern is generated using a very worn, genuine $20 bill, thediscrimination system may reject an unacceptable number of genuine butcrisp $20 bills.

It has been found that scanning U.S. bills of different denominationsalong a central portion thereof provides scanning patterns sufficientlydivergent to enable accurate discrimination between differentdenominations. Such a discrimination device is disclosed in U.S. Pat.No. 5,295,196. However, currencies of other countries can differ fromU.S. currency and from each other in a number of ways. For example,while all denominations of U.S. currencies are the same size, in manyother countries currencies vary in size by denomination. Furthermore,there is a wide variety of bill sizes among different countries. Inaddition to size, the color of currency can vary by country and bydenomination. Likewise, many other characteristics may vary betweenbills from different countries and of different denominations.

As a result of the wide variety of currencies used throughout the world,a discrimination system designed to handle bills of one countrygenerally can not handle bills from another country. Likewise, themethod of discriminating bills of different denominations of one countrymay not be appropriate for use in discriminating bills of differentdenominations of another country. For example, scanning for a givencharacteristic pattern along a certain portion of bills of one country,such as optical reflectance about the central portion of U.S. bills, maynot provide optimal discrimination properties for bills of anothercountry, such as German marks.

Furthermore, there is a distinct need for an identification system whichis capable of accepting bills of a number of currency systems, that is,a system capable of accepting a number of bill-types. For example, abank in Europe may need to process on a regular basis French, British,German, Dutch, etc. currency, each having a number of differentdenomination values.

Some of the optical scanning systems available today employ two opticalscanheads disposed on opposite sides of a bill transport path. One ofthe optical scanheads scans one surface (e.g., green surface) of acurrency bill to obtain a first set of reflectance data samples, whilethe other optical scanhead scans the opposite surface (e.g., blacksurface) of the currency bill to obtain a second set of reflectance datasamples. These two sets of data samples are then processed and comparedto stored characteristic patterns corresponding to the green surfaces ofcurrency bills of different denominations. If degree of correlationbetween either set of data samples and any of the stored characteristicpatterns is greater than a predetermined threshold, then thedenomination of the bill is positively identified.

A drawback of the foregoing technique for scanning both surfaces of acurrency bill is that it is time-consuming to process and compare bothsets of data samples for the scanned bill to the stored characteristicpatterns. The set of data samples corresponding to the black surface ofthe scanned bill are processed and compared to the stored characteristicpatterns even though no match should be found. As previously stated, thestored characteristic patterns correspond to the green surfaces ofcurrency bills of different denominations.

Another drawback of the foregoing scanning technique is that the set ofdata samples corresponding to the black surface of the scanned billoccasionally leads to false positive identification of a scanned bill.The reason for this false positive identification is that if a scannedbill is slightly shifted in the lateral direction relative to the billtransport path, the set of data samples corresponding to the blacksurface of the scanned bill may sufficiently correlate with one of thestored characteristic patterns to cause a false positive identificationof the bill. The degree of correlation between the set of “black” datasamples and the stored “green” characteristic patterns should, ofcourse, not be greater than the predetermined threshold for positivelyidentifying the denomination of the bill.

Furthermore, in currency discriminating systems that rely on comparisonsbetween a scanned pattern obtained from a subject bill and sets ofstored master patterns, the ability of a system to accurately line upthe scanned patterns to the master patterns to which they are beingcompared is important to the ability of a discrimination system todiscriminate among bills of various denominations as well as betweengenuine bills and counterfeit bills without rejecting an unacceptablenumber of genuine bills. However, the ability of a system to line upscanned and master patterns is often hampered by the improper initiationof the scanning process which results in the generation of scannedpatterns. If the generation of scanned patterns is initiated too earlyor too late, the resulting pattern will not correlate well with themaster pattern associated with the identity of the currency; and as aresult, a genuine bill may be rejected. There are a number of reasonswhy a discrimination system may initiate the generation of a scannedpattern too early or too late, for example, stray marks on a bill, thebleeding through of printed indicia from one bill in a stack onto anadjacent bill, the misdetection of the beginning of the area of theprinted indicia which is desired to be scanned, and the reliance on thedetection of the edge of a bill as the trigger for the scanning processcoupled with the variance, from bill to bill, of the location of printedindicia relative to the edge of a bill. Therefore, there is a need toovercome the problems associated with correlating scanned and masterpatterns.

In some currency discriminators bills are transported, one at a time,passed a discriminating unit. As the bills pass the discriminating unit,the denomination of each bill is determined and a running total of eachparticular currency denomination and/or of the total value of the billsthat are processed is maintained. A number of discriminating techniquesmay be employed by the discriminating unit including optical or magneticscanning of bills. A plurality of output bins are provided and thediscriminator includes means for sorting bills into the plurality ofbins. For example, a discriminator may be designed to recognize a numberof different denominations of U.S. bills and comprise an equal number ofoutput bins, one associated with each denomination. These discriminatorsalso include a reject bin for receiving all bills which cannot beidentified by the discriminating unit. These bills may later be examinedby an operator and then either re-fed through the discriminator or setaside as unacceptable.

Depending on the design of a discriminator, bills may be transported andscanned either along their long dimension or their narrow dimension. Fora discriminator that transport bills in their narrow dimension, it ispossible that a given bill may be oriented either face up or face downand either top edge first (“forward” direction) or top edge last(“reverse” direction). For discriminators that transport bills in theirlong dimension, it is possible that a given bill may be oriented eitherface up or face down and either left edge first (“forward” direction) orleft edge last (“reverse” direction). The manner in which a bill must beoriented as it passes a discriminating unit depends on thecharacteristics of the discriminator. Some discriminators are capable ofidentifying the denomination of a bill only if it is fed with a preciseorientation, e.g., face up and top edge first. Other discriminators arecapable of identifying bills provided they are “faced” (i.e., fed with apredetermined face orientation, that is all face up or all face down).For example, such a discriminator may be able to identify a bill fedface up regardless of whether the top edge is fed first or last. Otherdiscriminators are capable of identifying the denomination fed with anyorientation. However, whether a given discriminator can discriminatebetween bills fed with different orientations depends on thediscriminating method used. For example, a discriminator thatdiscriminates bills based on patterns of transmitted light may be ableto identify the denomination of a forward fed bill regardless of whetherthe bill is fed face up or face down, but the same discriminator wouldnot be able to discriminate between a bill fed face up and a bill fedface down.

Currently, discriminators are known which discriminate and/or sort bydenomination when bills are properly faced. In such systems, allreverse-faced bills are not identified and are routed to a rejectreceptacle. Also discriminators are known which discriminate and/or sortbetween all bills facing up and all bills facing down. For example, in amulti-output pocket system, all face up bills, regardless ofdenomination, may be routed to a first pocket and all face down bills,regardless of denomination, may be routed to a second pocket.Furthermore, there is currently known discriminators designed to accepta stack of faced bills and flag the detection of a reverse-faced bill,thus allowing the reverse-faced bill to be removed from the stack.However, there remains a need for a discriminator that can detect andflag the presence of a bill oriented with an incorrect forward/reverseorientation and a discriminator that can sort between forward-orientedbills and reverse-oriented bills.

Furthermore, for a number of reasons, a discriminating unit may beunable to determine the denomination of a bill. These reasons include abill being excessively soiled, worn, or faded, a bill being torn orfolded, a bill being oriented in a manner that the discriminating unitcannot handle, and the discriminating unit having poor discriminatingperformance. Furthermore, the discriminating unit and/or a separateauthenticating unit may determine that a bill is not genuine. In currentdiscriminators, such unidentified or non-genuine bills are deposited ina reject receptacle.

A characteristic of the above described discriminators is that the valueof any rejected unidentified bills is not added to the running total ofthe aggregate value of the stack of bills nor do the counters keepingtrack of the number of each currency denomination reflect the rejectedunidentified bills. While this is desirable with respect to bills whichare positively identified as being fake, it may be undesirable withrespect to bills which were not identified for other reasons even thoughthey are genuine bills. While the bills in a reject receptacle may bere-fed through the discriminator, the operator must then add the totalsfrom the first batch and the second batch together. Such a procedure canbe inefficient in some situations. Also, if a bill was rejected thefirst time because it was, for example, excessively soiled or too worn,then it is likely that the bill will remain unidentified by thediscriminating unit even if re-fed.

A problem with the above described situations where the totals and/orcounts do not reflect all the genuine bills in a stack is that anoperator must then count all the unidentified genuine bills by hand andadd such bills to separately generated totals. As a result the chancefor human error increases and operating efficiency decreases. Take forexample a bank setting where a customer hands a teller a stack ofcurrency to be deposited. The teller places the stack of bills in adiscriminator, the display on the discriminator indicates that a totalof $730 has been identified. However, fourteen genuine bills remainunidentified. As a result, the teller must count these fourteen bills byhand or re-fed through the discriminator and then add their total to the$730 total. An error could result from the teller miscounting theunidentified bills, the teller forgetting to add the two totalstogether, or the teller overlooking the unidentified bills entirely andonly recording a deposit of $730. Moreover, even if the teller makes nomistakes, the efficiency of the teller is reduced by having to manuallycalculate additional totals. The decrease in efficiency is furtheraggravated where detailed records must be maintained about the specificnumber of each denomination processed during each transaction.

Therefore, there is a need for a currency discriminator which is capableof conveniently and efficiently accommodating genuine bills that, forwhatever reason, remain unidentified after passing through thediscriminating unit of a discriminator.

A number of methods have been developed for authenticating thegenuineness of security documents. These methods include sensingmagnetic, optical, conductive, and other characteristics of documentsunder test. In general, it has been found that no single authenticationtest is capable of detecting all types of counterfeit documents while atthe same time not rejecting any genuine documents. Therefore, more thanone test may be employed whereby a first test is used to detect certaintypes of counterfeits and additional tests are used to detect othertypes of counterfeits.

It has been known that the illumination of certain substances withultraviolet light causes the substances to fluoresce, that is, to emitvisible light. Some documents employ fluorescent materials as a securityfeature to inhibit counterfeiting. Typically, these fluorescent securityfeatures comprise a marking which is visibly revealed when the documentis illuminated with ultraviolet light. Previous methods have beendeveloped to authenticate such documents by sensing the fluorescentlight emitted by a document illuminated by ultraviolet light andcomparing the sensed fluorescent light to the fluorescent light emittedby genuine documents.

Conversely, some documents, such as U.S. currency, are manufactured fromspecial paper designed not to fluoresce under ultraviolet light.Previously known authenticating methods for such documents have sensedfor the emission of fluorescent light under ultraviolet illumination andhave rejected as counterfeit those documents emitting fluorescent light.

However, it has been found that the presently known ultravioletauthentication methods do not detect all types of counterfeits. Forexample, while many counterfeit U.S. bills do emit fluorescent lightunder ultraviolet illumination, some counterfeit U.S. bills do not.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved methodand apparatus for identifying documents.

It is an object of the present invention to provide an improved methodand apparatus for identifying, authenticating, and counting currencybills comprising a plurality of currency denominations.

It is an object of the present invention to provide an improved methodand apparatus for discriminating among documents of different typesincluding currency documents of different denominations.

It is an object of the present invention to provide an improved methodand apparatus for discriminating among currency bills comprising aplurality of currency denominations.

It is another object of this invention to provide-an improved method andapparatus of the above kind which is capable of efficientlydiscriminating among, authenticating, and counting bills of severalcurrency denominations at a high speed and with a high degree ofaccuracy.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of efficientlydiscriminating currencies from a number of different countries.

It is another object of this invention to provide a currency evaluationdevice able to discriminate among different denominations of bills fromtwo or more currency systems.

It is another object of this invention to provide a currency evaluationdevice able to discriminate among different denominations of bothCanadian and German bills.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of scanning a document suchas a currency bill along two or more laterally displaced segments tothereby identify the document.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of scanning a documentalong two or more laterally displaced segments by using two or morelaterally displaced scanheads.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of scanning a documentalong two or more laterally displaced segments by using two or morelaterally displaced sensors of a linear array scanhead.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of scanning a documentalong two or more laterally displaced segments by using one or morelaterally moveable scanheads.

It is another object of this invention to provide an improved method andapparatus of the above kind wherein the above scanheads or sensorsretrieve optical reflectance information from a document under test anduse such reflectance information to determine the identity of thedocument.

It is another object of this invention to provide an improved method andapparatus of the above kind which identifies a document by comparing oneor more scanned patterns generated by scanning a document under testwith one or more scanheads or one or more sensors and comparing thescanned pattern or patterns with one or more master patterns associatedwith genuine documents.

It is another object of this invention to provide an improved method andapparatus of the above kind which identifies a document by determiningthe size of the document.

It is another object of this invention to provide an improved method andapparatus of the above kind which identifies a document by determiningthe color of the document.

It is another object of this invention to provide an improved method andapparatus of the above kind which identifies a document based on acombination of size information and scanned/master pattern comparison.

It is another object of this invention to provide an improved method andapparatus of the above kind which identifies a document based on acombination of color information and scanned/master pattern comparison.

It is another object of this invention to provide an improved method andapparatus of the above kind which identifies a document based on acombination of size information, color information, and scanned/masterpattern comparison.

It is another object of this invention to provide an improved method andapparatus of the above kind in which only selected ones of a number ofscanheads or sensors are activated to scan a document.

It is another object of this invention to provide an improved method andapparatus of the above kind in which scanned patterns are generated onlyfrom the output or data derived therefrom of selected ones of a numberof scanheads or sensors which are activated to scan a document.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the selection of one or more of anumber of scanheads or sensors to scan a document is based on sizeinformation.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the selection of one or more of anumber of scanheads or sensors to scan a document is based on colorinformation.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the lateral positioning of one ormore moveable scanheads is based on size and/or color informationdetected from the document.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the selection of the output or dataderived therefrom of one or more of a number of scanheads or sensors forthe generation of scanned patterns is based on size information.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the selection of the output or dataderived therefrom of one or more of a number of scanheads or sensors forthe generation of scanned patterns is based on color information.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of scanning either side orboth sides of a document.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the amount of information that mustbe processed is reduced by tailoring the areas from which scannedpatterns are derived, such reduction being based on pre-scan informationdetected from a document such as the size and/or color of a document tobe scanned.

It is another object of this invention to provide an improved method andapparatus of the above kind in which the amount of information that mustbe processed is reduced by tailoring the data which must be assembledinto one or more scanned patterns, such reduction being based oninformation detected from a document during the scanning process itself,the information detected during the scanning process itself including,for example, size and/or color information.

It is another object of this invention to provide an improved method andapparatus of the above kind in which size and/or color informationdetected from a document is used to generate a preliminary set ofpotentially matching documents and in which one or more scanned patternsgenerated from a document are compared with master patterns chosen fromthe preliminary set.

It is another object of this invention to provide an improved method andapparatus of the above kind in which a document to be scanned istransported past one or more scanheads in a centered or justified manneralong a transport path.

It is another object of this invention to provide an improved method andapparatus of the above kind in which a document to be scanned istransported past one or more scanheads along a transport path and inwhich one or more sensors separate from the one or more scanheads areused to determine the lateral positioning of the document within thetransport path.

It is another object of this invention to provide an improved method andapparatus of the above kind in which a document to be scanned istransported past one or more scanheads along a transport path and inwhich the lateral positioning of the document within the transport pathis determined by analyzing the output of one or more scanheads.

It is another object of this invention to provide an improved method andapparatus of the above kind in which a document to be scanned istransported past one or more scanheads along a transport path and inwhich the skew of the document is determined by analyzing of output ofone or more scanheads or analyzing the output of one or more separatesensors.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of accepting documents fedeither face up or face down.

It is another object of this invention to provide an improved method andapparatus of the above kind which is capable of accepting documents fedin either the forward or reverse direction, i.e., top edge first or topedge last.

A related object of the present invention is to provide such an improvedcurrency discrimination and counting apparatus which is compact,economical, and has uncomplicated construction and operation.

It is an object of the present invention to provide an improved currencyscanning and counting machine which is relatively simple and compact,while at the same time providing a variety of advanced features whichmake the machine convenient and useful to the operator.

Another object of this invention is to provide such an improved currencyscanning and counting machine that is relatively inexpensive tomanufacture and maintain, and which also facilitates service andmaintenance. In this connection, a related object of the invention is toprovide such a machine having a relatively small number of parts, and inwhich most of the parts are arranged in a manner to have a longoperating life with little or no maintenance.

It is a further object of this invention to provide such a machine thatis capable of operating at a faster throughput rate than any previousmachine able to determine the denomination of the scanned bills.

It is another object of the present invention to provide an improvedmethod and apparatus for identifying a currency as belonging to a set ofone or more currency bills.

It is another object of the present invention to provide an improvedmethod and apparatus for determining the identity of a currency bill.

It is another object of the present invention to provide an improvedmethod of generating modified scanned patterns.

It is another object of the present invention to provide an improvedmethod of generating modified master patterns.

It is another object of the present invention to provide an improvedmethod and apparatus for determining the identity of a currency bill bycomparing a modified version of a scanned pattern with one or moremaster patterns.

It is another object of the present invention to provide an improvedmethod and apparatus for determining the identity of a currency bill bycomparing modified versions of one or more master patterns with ascanned pattern.

It is another object of the present invention to provide an improvedmethod and apparatus using an improved pattern generation method forimproving the ability of a discrimination system to accurately rejectimproper bills while reducing the likelihood of rejecting genuine bills.

It is another object of this invention to provide an improved documentcounting and discriminating apparatus that is capable of flaggingunidentified bills.

It is another object of this invention to provide an improved documentcounting and discriminating apparatus that flags unidentified bills bysuspending operation of the apparatus.

It is another object of this invention to provide an improved documentcounting and discriminating apparatus of the above type that canconveniently be caused to resume operation after an operator of theapparatus has examined an unidentified bill.

It is another object of this invention to provide an improved documentcounting and discriminating apparatus of the above type whereby thedenomination or kind of any unidentified bill may be conveniently addedto appropriate counters and the operation of the apparatus convenientlyresumed when an operator determines that an unidentified bill isacceptable and whereby the operation of the apparatus may beconveniently resumed without adversely affecting any counter when anoperator determines that an unidentified bill is not acceptable.

It is another object of this invention to provide an improved documentcounting and discriminating apparatus whereby the discriminator promptsthe operator as to the identity of any flagged bills, such as byprompting the operator as to the denomination of any bill whosedenomination has not been determined by the discriminator.

It is another object of this invention to provide an improved documentdiscriminating apparatus that can flag a document based on the forwardor reverse orientation of the document.

It is another object of this invention to provide an improved documentdiscriminating apparatus that can sort between documents having aforward orientation and documents having a reverse orientation.

It is another object of the present invention to provide an improvedmethod and apparatus for authenticating documents including currencydocuments.

It is another object of the present invention to provide an improvedmethod and apparatus for authenticating United States currency bills.

It is another object of the present invention to provide an improvedmethod and apparatus for authenticating documents which may be employedin a currency discriminating apparatus.

It is an object of the present invention to provide an improved methodand apparatus for authenticating documents including currency documentsby illuminating a document with ultraviolet light.

It is another object of the present invention to provide an improvedmethod and apparatus for authenticating documents which improves theability of a system to accurately reject improper documents whilereducing the likelihood of rejecting genuine documents.

Other objects and advantages of the invention will become apparent uponreading the following detailed description in conjunction with theaccompanying drawings.

In accordance with one embodiment of the present invention, theforegoing objectives are realized by providing a currency counting anddiscrimination device for receiving a stack of currency bills, rapidlycounting and discriminating the bills in the stack, and then re-stackingthe bills. This device includes an input receptacle for receiving astack of currency bills to be discriminated, a discriminating unit fordiscriminating the currency bills by denomination, an output receptaclefor receiving the currency bills after they have been discriminated, anda transport mechanism for transporting the currency bills, one at atime, from the input receptacle past the discriminating unit and to theoutput receptacle. The transport mechanism includes stripping wheels forstripping the lowermost bill from a stack of bills in the inputreceptacle, and a pair of driven transport rolls on opposite sides ofthe discriminating unit for transporting each bill past thediscriminating unit. One of the transport rolls also receives billsdirectly from the stripping wheels and transports the received bills tothe region between the pair of transport rolls.

In one embodiment, a pair of photosensors are located at opposite sidesof the bill transport path, each photosensor including a light sourceand a protective lens on one side of the bill, and a photodetector and aprotective lens on the other side of the bill. The lenses for both thelight sources and the photodetectors are located sufficiently close toeach other that the lenses are wiped by the bills transportedtherebetween.

In accordance with one embodiment of the present invention, theobjectives enumerated above are achieved by scanning a document alongone or more segments, generating one or more scanned patterns therefrom,and comparing the one or more scanned patterns to one or more masterpatterns associated with scans along corresponding segments of genuinedocuments. According to one embodiment, bills are fed in and scannedacross their narrow dimension. According to another embodiment, billsare fed in and scanned across their wide dimension. One embodiment ofthe present invention involves a technique based on the optical sensingof reflectance characteristics obtained by illuminating and scanning adocument such as a currency bill along an appropriately selected segmentor segments of a document. Light reflected from the bill as it isoptically scanned is detected and used as an analog representation ofthe variation in the dark and light content of the printed pattern orindicia on the bill surface.

A series of such detected reflectance signals are obtained by samplingand digitally processing, under microprocessor control, the reflectedlight at a plurality of predefined sample points as the bill is movedacross the illuminated strip. Accordingly, a fixed number of reflectancesamples is obtained across the note. The data samples obtained for abill scan are subjected to digital processing, including a normalizingprocess to deaccentuate variations due to contrast fluctuations in theprinted pattern or indicia existing on the surface of the bill beingscanned. The normalized reflectance data represent a characteristicpattern that is fairly unique for a given bill identity and incorporatessufficient distinguishing features between characteristic patterns fordifferent bill-types so as to accurately differentiate therebetween.

By using the above approach, a series of master characteristic patternsare generated and stored using standard bills for each denomination ofcurrency that is to be detected. The “standard” bills used to generatethe master characteristic patterns are preferably bills that areslightly used bills. According to one embodiment, two or fourcharacteristic patterns are generated and stored within system memoryfor each detectable bill-type. The stored patterns correspond,respectively, to optical scans performed on one or both sides of a billalong “forward” and “reverse” directions relative to the pattern printedon the bill. For bills which produce significant pattern changes whenshifted slightly to the left or right, such as the $10 bill in U.S.currency, it is preferred to store two patterns for each of the“forward” and “reverse” directions, each pair of patterns for the samedirection represent two scan areas that are slightly displaced from eachother along the lateral dimension of the bill. The documentidentification system of this invention may be adapted to identifydifferent denominations of a plurality of currency systems. Accordingly,a master set of different characteristic patterns is stored within thesystem memory for subsequent correlation purposes.

According to one embodiment a master pattern for a given denomination isgenerated by averaging a plurality of component patterns, typicallythree, each generated by scanning a genuine bill of the givendenomination.

According to one method, a master pattern for a given denomination isgenerated by averaging a plurality of component patterns, wherein thecomponent patterns are generated by scanning one or more genuine billsof “standard” or average quality of the given denomination. A “standard”bill is a slightly used bill, as opposed to a crisp new bill or onewhich has been subject to a high degree of usage.

According to another method, a master pattern for a given denominationis generated by averaging a plurality of component patterns, whereinsome of the component patterns are generated by scanning one or more newbills of the given denomination and some of the component patterns aregenerated by scanning one or more old bills of the given denomination.

According to the correlation technique of this invention, the patterngenerated by scanning a bill under test and processing the sampled datais compared with each of the prestored characteristic patterns within apreliminary set (to be described below) to generate, for eachcomparison, a correlation number representing the extent of similaritybetween corresponding ones of the plurality of data samples for thecompared patterns. Bill identification is based on designating thescanned bill as belonging to the bill-type corresponding to the storedcharacteristic pattern for which the correlation number resulting frompattern comparison is determined to be the highest. The possibility of ascanned bill having its identity mischaracterized following thecomparison of characteristic patterns is significantly reduced bydefining a bi-level threshold of correlation that must be satisfied fora “positive” call to be made.

In essence, the present invention utilizes an optical sensing andcorrelation technique for positively identifying any of a plurality ofdifferent bill-types regardless of whether the bill is scanned along the“forward” or “reverse” directions. Likewise in one embodiment of thepresent invention, the system is capable of identifying any of aplurality of different bill-types regardless of whether the bill is fedinto the system with a “face up” or “face down” orientation. Faceorientation can be accommodated by storing master patterns scanned fromboth sides of genuine documents, using a system having one or morescanheads on a single side of a document transport path, and comparingscanned patterns to master patterns retrieved from both sides of genuinedocuments. Alternatively, scanheads may be placed on both sides of adocument transport path, scanned patterns retrieved from respectivesides can be compared to master patterns from both sides or masterpatterns from corresponding sides where face orientation can bedetermined. Additionally, a cross check can be performed so that theidentity determined by a match of patterns from one side of a documentis consistent with the identity indicated by comparing patterns from theother side of the document. For both one-sided and two-sided scanheadsystems, where the face orientation of a document can be determinedbefore patterns are compared, scanned patterns from one side of adocument can be compared only to master patterns retrieved from acorresponding side. Similar methods can be employed for accommodatingdocuments fed in forward and reverse directions.

In one embodiment, the invention is particularly adapted to beimplemented with a system programmed to track each identified currencyidentity so as to conveniently present aggregate totals for bills thathave been identified at the end of a scan run. One embodimentincorporates an abbreviated curved transport path for accepting currencybills that are to be counted and transporting the bills about theirnarrow dimension across a scanhead located downstream of the curved pathand onto a conventional stacking station where sensed and counted billsare collected. In one embodiment, a scanhead of the present inventionoperates in conjunction with an optical encoder which is adapted toinitiate the capture of a predefined number of reflectance data sampleswhen a bill (and, thus, the indicia or pattern printed thereupon) movesacross a coherent strip of light focused by the scanhead.

In one embodiment, a scanhead of the present invention uses a pair oflight-emitting diodes (“LEDs”) to focus a coherent light strip ofpredefined dimensions and having a normalized distribution of lightintensity across the illuminated area. The LEDs are angularly disposedand focus the desired strip of light onto the narrow dimension of a billpositioned flat across the scanning surface of the scanhead. Aphotodetector detects light reflected from the bill. The sampling of thephotodetector output is controlled by the optical encoder to obtain thedesired reflectance samples. In one embodiment, initiation of samplingis based upon detection of the edge of a bill. In another embodiment forbills having a borderline surrounding the remaining printed indicia,initiation of sampling is based upon detection of the borderline of abill.

Some of the above described techniques and apparatus as tailored toscanning U.S. currency are more fully disclosed in U.S. Pat. No.5,295,196, for a “Method and Apparatus for Currency Discrimination andCounting” incorporated herein in its entirety.

In adapting the currency discriminating method and apparatus disclosedin U.S. Pat. No. 5,295,196 to optimize the scanning of currencies fromcountries other than the United States, it is first noted that while ithas been found that scanning along the central portion of the green sideof U.S. bills provides good patterns to discriminate between thedifferent U.S. denominations, foreign bills may require scanning alongsegments located in locations other than the center and the desirableareas to scan bills can vary from bill-type to bill-type. For example,it may be determined that it is desirable to scan German marks in theforward direction along a segment 1 inch (2.54 cm) to the left of centeralong the top face of a bill while it may be desirable to scan Britishpounds along a segment 1.5 inches (3.81 cm) to the right of center. Toprovide a system capable of scanning along a plurality of laterallydisplaced segments, the present invention utilizes either a plurality oflaterally displaced stationary scanheads, one or more laterally moveablescanheads, or a linear array scanhead having a plurality of laterallydisplaced sensors. In one embodiment, the scanheads or sensors arearranged in a symmetrical manner about the center of document to bescanned. Such a symmetrical arrangement aids in providing a system whichis capable of accepting bills fed in both the forward and reversedirections.

Additionally, while all denominations of U.S. currency have the samesize, currencies from other countries may vary in size from country tocountry as well as from denomination to denomination for currency fromthe same country. In one embodiment of the present invention, variancein size is accommodated by incorporating means for determining the sizeof a document. These size determining means may include sensors separatefrom the scanheads or scanning sensors discussed above or alternatively,in some embodiments of the present invention, may include the scanheadsor scanning sensors discussed above which are used for the retrieval ofscanned characteristic patterns. Based on the size information retrievedfrom a bill, selected scanheads may be activated, laterally moveablescanheads may be appropriately positioned and activated, and/or selectedsensors in a linear array scanhead may be activated to permit scanningalong appropriate segments of a bill based on its size. Alternatively,all scanheads or scanning sensors may be activated and the output ofappropriately positioned scanheads or scanning sensors may be processedto generate scanned patterns based on the size of a bill. Furthermore,based on the size of a bill, a preliminary determination can be made asto which of a plurality of genuine bill-types a bill under test maypotentially match. Based on such a preliminary determination, thecomparison of generated scanned patterns can be limited to only masterpatterns associated with bill-types chosen from the preliminary set ofpotentially matching bills.

Likewise, the transport mechanism which transports documents to bescanned past the above described scanheads may be designed to transportdocuments in a centered manner, left or right justified manner, in anon-controlled lateral positioned manner, in a non-skewed manner, or ina skewed manner. Sensors separate and distinct from the above describedscanheads or the above described scanheads themselves may be used todetermine the lateral positioning of transported bills and/or theirdegree of skew. Based on a determination of the lateral positioning of abill and/or its skew, appropriately positioned scanheads or scanningsensors may be activated or laterally moveable scanheads may beappropriately positioned and activated or the output from appropriatelypositioned scanheads or scanning sensors may be processed to generatescanned patterns based on the lateral positioning and/or skew of thebill.

Additionally, while all denominations of U.S. currency have the samecolors (a “green” side and a “black” side), currencies from othercountries may vary in color from country to country as well as fromdenomination to denomination for currency from the same country. In oneembodiment of the present invention, variance in color is accommodatedby incorporating means for determining the color of a document. Thesecolor determining means may include sensors separate from the scanheadsor sensors discussed above or alternatively, in some embodiments of thepresent invention, may include the appropriately modified scanheads orsensors discussed above which are used for the retrieval of scannedcharacteristic patterns. For example, colored filters may be placed infront of the above described scanheads or sensors. Based on the colorinformation retrieved from a bill, selected scanheads may be activated,laterally moveable scanheads may be appropriately positioned andactivated, and/or selected sensors in a linear array scanhead may beactivated to permit scanning along appropriate segments of a bill basedon its color. Alternatively, all scanheads or scanning sensors may beactivated and the output of appropriately positioned scanheads orscanning sensors may be processed to generate scanned patterns based onthe color of a bill. Furthermore, based on the color of a bill, apreliminary determination can be made as to which of a plurality ofgenuine bill-types a bill under test may potentially match. Based onsuch a preliminary determination, the comparison of generated scannedpatterns can be limited to only master patterns associated withbill-types chosen from the preliminary set of potentially matchingbills.

In one embodiment of the present invention, both color and sizeinformation may be utilized as described above.

In one embodiment of the present invention, scanheads are positioned onboth sides of a document transport path so as to permit scanning ofeither or both sides of a document.

According to one embodiment, an apparatus for currency discriminationcomprises first and second stationary scanheads, disposed on oppositesides of a bill transport path, for scanning respective first and secondopposing surfaces of a bill traveling along the bill transport path andfor producing respective output signals. The bill travels along thetransport path in the direction of a predetermined dimension of thebill. A memory stores master characteristic patterns corresponding toassociated predetermined surfaces (e.g., green surfaces) of a pluralityof denominations of genuine bills. Sampling circuitry samples the outputsignals associated with the respective first and second opposingsurfaces of the scanned bill. A signal processor is programmed todetermine which one of the first and second opposing surfacescorresponds to the associated predetermined surfaces of the plurality ofdenominations of genuine bills. According to one embodiment adapted fordiscriminating, for example, U.S. bills, the determination as to whichsurface of a bill corresponds to a predetermined surface is made bydetecting the borderlines on each side of a bill and determining therelative times of detection of each borderline. The processor thencorrelates the output signal associated with the one of the first andsecond opposing surfaces corresponding to the associated predeterminedsurfaces with the master characteristic patterns. If the degree ofcorrelation between the selected output signal and any of the storedcharacteristic patterns is greater than a predetermined threshold, thenthe denomination of the bill is positively identified.

For each scanhead, initiation of sampling is based upon detection of thechange in reflectance value that occurs when the outer border of theprinted pattern on a bill is encountered relative to the reflectancevalue obtained at the edge of the bill where no printed pattern exists.According to one embodiment of this invention, illuminated strips of atleast two different dimensions are used for the scanning process. Anarrow strip is used initially to detect the starting point of theprinted pattern on a bill and is adapted to distinguish the thinborderline that typically marks the starting point of and encloses theprinted pattern on a bill. For the rest of the preselected dimensionscanning following detection of the borderline of the printed pattern, asubstantially wider strip of light is used to collect the predefinednumber of samples for a bill scan. The generation and storage ofcharacteristic patterns using standard notes and the subsequentcomparison and correlation procedure for classifying the scanned bill asbelonging to one of several predefined currency denominations is basedon the above-described sensing and correlation technique.

Furthermore, in accordance with another feature of the presentinvention, the objectives enumerated above in connection withcorrelating patterns are achieved by repetitively comparing a scannedpattern with multiple sets of master patterns until a sufficient matchis found, or alternatively, by repetitively comparing a set of originalmaster patterns with multiple scanned patterns until a sufficient matchis found. The multiple sets of master patterns comprise an original setof master patterns plus one or more sets of modified versions of theoriginal master patterns. The multiple scanned patterns comprise anoriginal scanned pattern plus one or more modified versions of theoriginal scanned patterns. Each modified pattern comprises one or morereplicated data values from a corresponding original pattern to whicheach modified pattern is to be compared. Alternatively, each modifiedmaster pattern comprises one or more data values which are set equal tozero.

Briefly, in accordance with one embodiment, an improved method ofgenerating modified scanned or master patterns for use in adiscrimination system capable of identifying one or more currency billsis provided. Each of the scanned and master patterns comprises asequence of data values representing analog variations of characteristicinformation along a segment of a bill and each pattern has a leading endand a trailing end. Each of the data values has an associated sequenceposition. The modified scanned or master patterns are generated bydesignating either the scanned pattern or the master pattern formodification and inserting a predetermined number, R, of data values ateither the trailing end of the sequence of data values of the designatedpattern when the modification is performed in the forward direction orthe leading end of the sequence of data values of the designated patternwhen the modification is performed in the backward direction. Thismodification effectively removes R data values from the leading ortrailing end of the designated pattern. Either the last R data values ofthe designated pattern are set equal to the last R data values of thenon-designated pattern when the modification is performed in the forwarddirection or the first R data values of the designated pattern are setequal to the first R data values of the non-designated pattern when themodification is performed in the backward direction. Alternatively, themodified master patterns are generated by inserting R data samples atthe leading or trailing ends of the master patterns and by setting thefirst R or last R data samples of the modified master pattern equal tozero.

According to one method, a modified scanned pattern is generated byremoving a predetermined number of leading or trailing data values of anoriginal scanned pattern. Trailing or leading data values, respectively,are added to the modified scanned pattern with the added data valuesbeing copied from corresponding sequence positions of a correspondingmaster pattern. Alternatively, instead of explicitly removing leading ortrailing data values, the leading or trailing data values may beeffectively removed by adding data values to the opposite end of thescanned pattern and treating the modified scanned pattern as notincluding the “removed” leading or trailing data values.

According to another method, a modified master pattern is generated in asimilar manner except that added trailing or leading data values of themodified master pattern are set equal to data values copied fromcorresponding sequence positions of a scanned pattern.

According to another method, a modified master pattern is generated in asimilar manner except that added trailing or leading data values of themodified master pattern are set equal to zero.

The above described modified patterns or pattern generation methods maybe employed in currency identification systems to compensate formisalignment between scanned and master patterns.

According to another method, a scanned pattern comprising a number ofdata values is compared with one or more master patterns also comprisinga number of data values. The scanned and master patterns representanalog variations in characteristic information retrieved from billsalong corresponding segments. For example, the patterns may comprise 64data values generated by sampling the output of a photodetector as abill is moved relative to a scanhead, the output of the photodetectorrepresenting analog variation in the reflectance of light along a givensegment of the bill. If none of the master patterns sufficiently matchthe scanned pattern, the scanned pattern may be modified and themodified scanned pattern compared to the master patterns. For example,data values #1 and #2 may be removed from the scanned pattern sequence,scanned patterns #3 and #4 may be made the first and second values inthe modified sequence with subsequent data values modified accordingly.As a result of such a process, the original data values #63 and #64 nowbecome modified data values #61 and #62. As a result of the above stepsan incomplete modified pattern of data values #1-#62 is generated.According to one embodiment, modified data values #63 and #64 aregenerated by replicating data values #63 and #64 of the master patternsto which the modified scanned pattern is to be compared. If the modifiedpatterns do not sufficiently match any of the master patterns, themodification process may be reiterated except that new scanned modifiedvalues #61-#64 are generated by replicating master pattern values#61-#64. This process is repeated until a sufficient match is found oruntil a predetermined number of modification iterations have occurred.

According to another embodiment, scanned patterns may be modifiedbackwards instead of the forward modification described above.

According to another embodiment, master patterns may be modified insteadof scanned patterns. According to this method, data values from scannedpatterns are replicated into appropriate locations in modified masterpattern sequences.

According to another embodiment, trailing or leading sequence positionsof modified master patterns may be filled with zeros instead ofreplicated data values from a scanned pattern to which modified masterpatterns are to be compared.

According to another embodiment, modified master patterns with trailingor leading data values equal to zero are stored in a memory of anidentification system along with corresponding unmodified masterpatterns, the master patterns and modified master patterns being storedbefore a bill under test is scanned by the identification system. When abill under test is scanned by the identification system it is comparedto one or more of the master patterns. If the identity of the bill cannot be determined based on this comparison, the scanned pattern iscompared with one or more of the modified master patterns. This processcan be repeated, with the scanned pattern being compared to multiplymodified master patterns if necessary.

According to another embodiment, a currency evaluation device isprovided that is able to discriminate among bills of differentdenominations from two or more currency systems. In one embodiment, sucha device is provided that is able to discriminate among both Canadianand German bills of different denominations. In one embodiment, such adevice utilizes three scanheads when scanning Canadian bills and asingle scanhead when scanning German bills. The device is able to acceptfaced Canadian and German bills fed in either the forward or reversedirections. According to one embodiment, the operator of the devicepre-declares whether Canadian or German bills are to be discriminated.According to one embodiment the measured length of the narrow dimensionof German bills is utilized in discriminating German bills. Toaccommodate for possible lateral shifting of bills relative to thescanhead, multiple German master patterns associated with laterallydisplaced scans are stored for some denominations. To accommodate forpossible lateral shifting of bills relative to the scanheads, multipleCanadian patterns associated with laterally displaced scans aregenerated and averaged in generated stored Canadian master patterns. Tocompensate for problems associated with triggering scanning relative tothe edge of a bill, multiple patterns are stored for both Canadian andGerman bills associated with both leading and lagging printed indicia.

In accordance with another embodiment of the present invention, acorrelation technique is utilized whereby a scanned pattern generatedfrom the green side of a test bill is correlated against storedgreen-side master patterns. If as a result of the green-sidecorrelation, the denomination of the test bill can not be called, ascanned pattern generated from the black side of the test bill iscorrelated against stored black-side master patterns. More particularly,if the green-side correlation results in an indication that the testbill is a $20, $50, or $100 bill but not with sufficiently highcertainty so as to permit calling the denomination of the test bill,then the black-side scanned pattern is correlated against one or moreblack-side master patterns, provided the best call green-sidecorrelation number is greater than a predetermined threshold.

According to one embodiment, documents, including currency bills, arediscriminated by comparing a scanned pattern retrieved from a first sideof a test document with one or more stored master patterns retrievedfrom a first side of one or more genuine documents and comparing ascanned pattern retrieved from a second side of a test document with oneor more stored master patterns retrieved from a second side of one ormore genuine documents.

According to one embodiment a currency discriminator is provided thatcounts and discriminates bills as they pass a discriminating unit andthat flags an unidentified bill or one having a predeterminedcharacteristic, for example a bill having a specified orientation, bytransferring the flagged bill to a location where it can be convenientlyexamined by an operator and then suspending the operation of thediscriminator. The operator may then examine the bill and determinewhether the bill is acceptable or not. Denomination selection elementssuch as keys are provided to enable the operator with the depression ofa single button to indicate the denomination of an unidentified butacceptable bill, to cause the value of the bill to be reflected in anyappropriate counters, and to cause the discriminator to resumeoperation. A continuation selection element is also provided to enablethe operator to cause the discriminator to resume operation withoutadversely affecting any counters when an unidentified bill is determinedto be unacceptable.

According to one embodiment of the present invention, a discriminator isprovided with a single output receptacle in which all bills are stackedafter they pass by the discriminating unit. When an unidentified bill isdetected, the discriminator halts operation with the unidentified billpositioned at a predetermined location within the stack such as at thetop or back of the stack of bills in the output receptacle or at apredetermined position just prior to the stack. The bill may then beconveniently examined by the operator.

According to another embodiment of the present invention, adiscriminator is provided with an examining station where unidentifiedbills are transferred before the discriminator halts operation. Upondetermination that a bill is acceptable, the bill may then betransferred to the output receptacle in a single output receptaclediscriminator or to an output receptacle associated with thedenomination or other characteristic of the bill in a multi-outputreceptacle discriminator. Additionally, a reject receptacle may beprovided for receiving bills which are determined to be unacceptable.

In one embodiment, a discriminator is provided with two or more outputreceptacles. All flagged bills are delivered to a separate outputreceptacle while the discriminator continues to process any remainingbills. Alternatively, bills that are positively determined to be suspectbills may be delivered to one output receptacle, all other flagged billsmay be delivered to a second output receptacle, and all unflagged andidentified bills may be delivered to one or more additional outputreceptacles. In another embodiment, suspect bills are routed to aseparate output receptacle while all other bills are routed to one ormore additional output receptacles.

The discriminator, in another embodiment is designed to suspendoperation upon encountering one or more types of flagged bills. Forexample, the discriminator may halt operation when a no call bill isdetected but not when a suspect bill is detected, e.g., when suspectbills are routed to an output receptacle separate from the outputreceptacle or receptacles to which other bills are routed. According toanother embodiment, the discriminator does not suspend its operationupon detecting a flagged bill but rather continues processing anyremaining bills, e.g., when flagged bills are routed to one or moreoutput receptacles separate from the output receptacle or receptacles towhich non-flagged bills are delivered.

According to one embodiment, the value of any flagged bill such as a nocall is reconciled on-the-fly, that is, at the time such bill isencountered. According to one such embodiment, the discriminatorsuspends operation until the value of the flagged bill is reconciled.

According to another embodiment, the value of any flagged bills isreconciled after all bills have been processed. Alternatively, thereconciliation process may begin before all bills have been processedbut without suspending the processing of the remaining bills.

According to one embodiment, denomination indicating means are providedto permit the operator to indicate the value of a flagged bill such as ano call. Examples of denomination indicating means include, for example,denomination selection elements such as keys, buttons, switches, lights,and displayed keys, denominations, or messages. Such elements may beselected by, for example, pressing an appropriate one of such elementsor using scroll keys. The selection of a denomination may cause thatdenomination to be indicated to the discriminator or, alternatively, adenomination may first have to be selected and then indicated to thediscriminator by selecting an accept, yes, or enter key.

According to one embodiment, prompting means are provided whereby thediscriminator is able to suggest a denomination to the operator of thediscriminator in connection with a flagged bill such as call. Examplesof criteria used in prompting a denomination to the operator inconnection with a flagged bill include suggesting a denomination or asequence of denominations based on a default basis, random basis,user-defined basis, manufacturer defined basis, last bill information,last no call information, last called denomination information,historical information, comparison of scanned and reference informationsuch as correlation information. Means for prompting a denomination mayinclude, for example, displaying a message, highlighting or illuminatinga denomination selection or indicating element or associated light.

According to another embodiment of the present invention, adiscriminator discriminates a stack of bills and flags bills having agiven forward/reverse orientation. Accordingly, when a stack of billspredominately oriented in the forward or reverse direction isdiscriminated by the discriminator, any bills oriented in the oppositeforward/reverse direction may be flagged. Any flagged bills may eitherbe removed without replacement or re-oriented in the appropriate forwardor reverse direction. As a result, a stack of bills may be generated inwhich all bills have the same forward/reverse orientation.Alternatively, in a multi-output receptacle discriminator, instead offlagging bills based on their forward/reverse orientation, bills havinga forward orientation may be routed to one output receptacle and thosehaving a reverse orientation may be routed to another output receptacle.

Likewise a discriminator may flag or sort bills based on their faceorientation, that is face up or face down, or bills not belonging to agiven denomination. Furthermore, the above criteria may be combined invarious operating modes of the discriminator.

In one embodiment, the discriminator optically scans an area of a billand generates a scanned pattern from optical reflectance samples. Ascanned pattern is compared with a plurality of master patternsassociated with genuine bills of different denominations. Furthermore,the discriminator may store master patterns associated with both forwardand reverse scans and/or both top surface and bottom surface scans ofgenuine bills.

In one embodiment, a bill is scanned for first and second characteristicinformation, utilizing the first characteristic information to determinethe denomination of a scanned bill, and using the second characteristicinformation to verify the genuineness of the bill. More particularly, acurrency evaluation device, according to the present invention,comprises detection circuitry for detecting first and secondcharacteristic information from a scanned bill, a memory for storingsets of genuine first and second characteristic information for aplurality of denominations of genuine bills, and signal processing meansfor comparing the detected first and second characteristic informationwith the stored genuine first and second characteristic information. Thesignal processing means performs a first comparison whereby the detectedfirst characteristic information is compared with the stored sets ofgenuine first characteristic information. This first comparison resultsin either an indication of the denomination of the scanned bill or anerror. The results of the first comparison are used to streamline asecond comparison between detected and stored second characteristicinformation. The second comparison compares the detected secondcharacteristic information with stored genuine second characteristicinformation corresponding to the denomination indicated by the firstcomparison. The second comparison results in either an indication of thegenuineness of the scanned bill or an error.

According to one embodiment of the present invention, a document to beauthenticated is illuminated with ultraviolet light and the amount ofultraviolet light which is reflected off the document is measured. Basedon the amount of ultraviolet light which is detected, the document iseither authenticated or rejected. In the case of documents beingauthenticated relative to United States currency, a bill is rejected ifa high level of reflected ultraviolet light is not detected.

In another embodiment, the above objectives are achieved by illuminatinga document with ultraviolet light and measuring both the amount ofreflected ultraviolet light and the amount of emitted visible light.Based on the amount of ultraviolet light detected and the amount ofvisible light detected, a document is either authenticated or rejected.In the case of documents being authenticated relative to United Statescurrency, a bill is rejected if either a high level of reflectedultraviolet light is not detected or even a low level of visible lightis detected.

As explained above, it is known that some counterfeit United Statesbills fluoresce, or emit visible light, when illuminated by ultravioletlight. As genuine United States currency does not fluoresce, theemission of visible light has been employed as a means of detectingcounterfeit United States currency. However, it has been found that notall counterfeit United States bills fluoresce; and hence, suchcounterfeits will not be detected by the above described fluorescencetest.

It has been found that genuine United States currency reflects a highlevel of ultraviolet light when illuminated by an ultraviolet lightsource. It has also been found that some counterfeit United States billsdo not reflect a high level of ultraviolet light. Such counterfeit billsmay or may not also fluoresce under ultraviolet light. The presentinvention employs an authentication test wherein the amount of reflectedultraviolet light is measured and a bill is rejected if it does notreflect a high amount of ultraviolet light. By employing such a test,counterfeit United States bills which do not reflect a high level ofultraviolet light may be properly rejected.

While not all counterfeit United States bills fail to reflect a highlevel of ultraviolet light and hence not all counterfeit United Statesbills will be detected using this test, the present invention providesan additional means for detecting counterfeit bills which mightotherwise go undetected. Furthermore, the likelihood of a counterfeitUnited States bill going undetected may be further reduced by employingan alternative embodiment of the present invention wherein both theamount of reflected ultraviolet light and the amount of emitted visiblelight are measured. In such a system, a bill is rejected as counterfeitif either it fails to reflect a high level of ultraviolet light or itfluoresces.

The above described embodiments may be adapted to authenticatecurrencies from other countries and other types of documents such asfood stamps and checks. For instance some genuine documents may bedesigned to reflect ultraviolet light only in certain locations and/orin a predetermined pattern. An alternative embodiment of the presentinvention may be designed to accept documents which exhibit similarcharacteristics while rejecting those which do not. Likewise, analternative embodiment of the present invention may be employed toauthenticate documents based on both their characteristics with respectto reflected ultraviolet light and their characteristics with respect tofluorescent emissions, e.g., detecting the amount, location, and/orpattern of fluorescent emissions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a currency scanning and counting machineembodying the present invention;

FIG. 2a is a functional block diagram of the currency scanning andcounting machine of FIG. 1 illustrating a scanhead arranged on each sideof a transport path;

FIG. 2b is a functional block diagram of the currency scanning andcounting machine illustrating a scanhead arranged on a single side of atransport path;

FIG. 2c is a functional block diagram of the currency scanning andcounting machine similar to that of FIG. 2b but illustrating the feedingand scanning of bills along their wide direction;

FIG. 2d is a functional block diagram of the currency scanning andcounting machine similar to that of FIGS. 2a-2 d illustrating theemployment of a second characteristic detector;

FIG. 3 is a diagrammatic perspective illustration of the successiveareas scanned during the traversing movement of a single bill across anoptical sensor according to one embodiment of the present invention;

FIGS. 4a and 4 b are perspective views of a bill and one area to beoptically scanned on the bill;

FIGS. 5a and 5 b are diagrammatic side elevation views of the scan areato be optically scanned on a bill according to embodiments of thepresent invention;

FIG. 6a is a perspective view of a bill showing the preferred area of afirst surface to be scanned by one of the two scanheads employed in oneembodiment of the present invention;

FIG. 6b is another perspective view of the bill in FIG. 6a showing thepreferred area of a second surface to be scanned by the other of thescanheads employed in one embodiment of the present invention;

FIG. 6c is a side elevation showing the first surface of a bill scannedby an upper scanhead and the second surface of the bill scanned by alower scanhead;

FIG. 6d is a side elevation showing the first surface of a bill scannedby a lower scanhead and the second surface of the bill scanned by anupper scanhead;

FIGS. 7a and 7 b form a block diagram illustrating one circuitarrangement for processing and correlating reflectance data according tothe optical sensing and counting technique of this invention;

FIGS. 8a and 8 b comprise a flowchart illustrating the sequence ofoperations involved in implementing a discrimination and authenticationsystem according to one embodiment of the present invention;

FIG. 9 is a flow chart illustrating the sequential procedure involved indetecting the presence of a bill adjacent the lower scanhead and theborderline on the side of the bill adjacent to the lower scanhead;

FIG. 10 is a flow chart illustrating the sequential procedure involvedin detecting the presence of a bill adjacent the upper scanhead and theborderline on the side of the bill adjacent to the upper scanhead;

FIG. 11a is a flow chart illustrating the sequential procedure involvedin the analog-to-digital conversion routine associated with the lowerscanhead;

FIG. 11b is a flow chart illustrating the sequential procedure involvedin the analog-to-digital conversion routine associated with the upperscanhead;

FIG. 12 is a flow chart illustrating the sequential procedure involvedin determining which scanhead is scanning the green side of a U.S.currency bill;

FIG. 13 is a flow chart illustrating the sequence of operations involvedin determining the bill denomination from the correlation results;

FIG. 14 is a flow chart illustrating the sequential procedure involvedin decelerating and stopping the bill transport system in the event ofan error;

FIG. 15a is a graphical illustration of representative characteristicpatterns generated by narrow dimension optical scanning of a $1 currencybill in the forward direction;

FIG. 15b is a graphical illustration of representative characteristicpatterns generated by narrow dimension optical scanning of a $2 currencybill in the reverse direction;

FIG. 15c is a graphical illustration of representative characteristicpatterns generated by narrow dimension optical scanning of a $100currency bill in the forward direction;

FIG. 15d is a graph illustrating component patterns generated byscanning old and new $20 bills according a second method according toone embodiment of the present invention;

FIG. 15e is a graph illustrating an pattern for a $20 bill scanned inthe forward direction derived by averaging the patterns of FIG. 15daccording a second method according to one embodiment of the presentinvention;

FIGS. 16a-e are graphical illustrations of the effect produced oncorrelation pattern by using the progressive shifting technique,according to an embodiment of this invention;

FIGS. 17a-17 c are a flowchart illustrating one embodiment of a modifiedpattern generation method according to the present invention;

FIG. 18a is a flow chart illustrating the sequential procedure involvedin the execution of multiple correlations of the scan data from a singlebill;

FIG. 18b is a flow chart illustrating a modified sequential procedure ofthat of FIG. 18a;

FIG. 19a is a flow chart illustrating the sequence of operationsinvolved in determining the bill denomination from the correlationresults using data retrieved from the green side of U.S. bills accordingto one embodiment of the present invention;

FIGS. 19b and 19 c are a flow chart illustrating the sequence ofoperations involved in determining the bill denomination from thecorrelation results using data retrieved from the black side of U.S.bills;

FIG. 20a is an enlarged vertical section taken approximately through thecenter of the machine, but showing the various transport rolls in sideelevation;

FIG. 20b is a top plan view of the interior mechanism of the machine ofFIG. 1 for transporting bills across the optical scanheads, and alsoshowing the stacking wheels at the front of the machine;

FIG. 21a is an enlarged perspective view of the bill transport mechanismwhich receives bills from the stripping wheels in the machine of FIG. 1;

FIG. 21b is a cross-sectional view of the bill transport mechanismdepicted in FIG. 21 along line 21 b;

FIG. 22 is a side elevation of the machine of FIG. 1, with the sidepanel of the housing removed;

FIG. 23 is an enlarged bottom plan view of the lower support member inthe machine of FIG. 1 and the passive transport rolls mounted on thatmember;

FIG. 24 is a sectional view taken across the center of the bottomsupport member of FIG. 23 across the narrow dimension thereof;

FIG. 25 is an end elevation of the upper support member which includesthe upper scanhead in the machine of FIG. 1, and the sectional view ofthe lower support member mounted beneath the upper support member;

FIG. 26 is a section taken through the centers of both the upper andlower support members, along the long dimension of the lower supportmember shown in FIG. 23;

FIG. 27 is a top plan view of the upper support member which includesthe upper scanhead;

FIG. 28 is a bottom plan view of the upper support member which includesthe upper scanhead;

FIG. 29 is an illustration of the light distribution produced about oneof the optical scanheads;

FIGS. 30a and 30 b are diagrammatic illustrations of the location of twoauxiliary photo sensors relative to a bill passed thereover by thetransport and scanning mechanism shown in FIGS. 20a-28;

FIG. 31 is a flow chart illustrating the sequential procedure involvedin a ramp-up routine for increasing the transport speed of the billtransport mechanism from zero to top speed;

FIG. 32 is a flow chart illustrating the sequential procedure involvedin a ramp-to-slow-speed routine for decreasing the transport speed ofthe bill transport mechanism from top speed to slow speed;

FIG. 33 is a flow chart illustrating the sequential procedure involvedin a ramp-to-zero-speed routine for decreasing the transport speed ofthe bill transport mechanism to zero;

FIG. 34 is a flow chart illustrating the sequential procedure involvedin a pause-after-ramp routine for delaying the feedback loon while thebill transport mechanism changes speeds;

FIG. 35 is a flow chart illustrating the sequential procedure involvedin a feedback loop routine for monitoring and stabilizing the transportspeed of the bill transport mechanism;

FIG. 36 is a flow chart illustrating the sequential procedure involvedin a doubles detection routine for detecting overlapped bills;

FIG. 37 is a flow chart illustrating the sequential procedure involvedin a routine for detecting sample data representing dark blemishes on abill;

FIG. 38 is a flow chart illustrating the sequential procedure involvedin a routine for maintaining a desired readhead voltage level;

FIG. 39 is a top view of a bill and size determining sensors accordingto one embodiment of the present invention;

FIG. 40 is a top view of a bill illustrating multiple areas to beoptically scanned on a bill according to one embodiment of the presentinvention;

FIG. 41a is a graph illustrating a scanned pattern which is offset froma corresponding master pattern;

FIG. 41b is a graph illustrating the same patterns of FIG. 41a after thescanned pattern is shifted relative to the master pattern;

FIG. 42 is a side elevation of a multiple scanhead arrangement accordingto one embodiment of the present invention;

FIG. 43 is a side elevation of a multiple scanhead arrangement accordingto another embodiment of the present invention;

FIG. 44 is a side elevation of a multiple scanhead arrangement accordingto another embodiment of the present invention;

FIG. 45 is a side elevation of a multiple scanhead arrangement accordingto another embodiment of the present invention;

FIG. 46 is a top view of a staggered scanhead arrangement according toone embodiment of the present invention;

FIG. 47a is a top view of a linear array scanhead according to oneembodiment of the present invention illustrating a bill being fed in acentered fashion;

FIG. 47b is a side view of a linear array scanhead according to oneembodiment of the present invention illustrating a bill being fed in acentered fashion;

FIG. 48 is a top view of a linear array scanhead according to anotherembodiment of the present invention illustrating a bill being fed in anon-centered fashion;

FIG. 49 is a top view of a linear array scanhead according to anotherembodiment of the present invention illustrating a bill being fed in askewed fashion;

FIGS. 50a and 50 b are a flowchart of the operation of a currencydiscrimination system according to one embodiment of the presentinvention;

FIG. 51 is a top view of a triple scanhead arrangement utilized in adiscriminating device able to discriminate both Canadian and Germanbills according to one embodiment of the present invention;

FIG. 52 is a top view of Canadian bill illustrating the areas scanned bythe triple scanhead arrangement of FIG. 51 according to one embodimentof the present invention;

FIG. 53 is a flowchart of the threshold tests utilized in calling thedenomination of a Canadian bill according to one embodiment of thepresent invention;

FIG. 54a illustrates the general areas scanned in generating master 10DM German patterns according to one embodiment of the present invention;

FIG. 54b illustrates the general areas scanned in generating master 20DM, 50 DM, and 100 DM German patterns according to one embodiment of thepresent invention;

FIG. 55 is a flowchart of the threshold tests utilized in calling thedenomination of a German bill according to one embodiment of the presentinvention;

FIG. 56 is a functional block diagram illustrating one embodiment of adocument authenticator and discriminator according to the presentinvention;

FIG. 57 is a functional block diagram illustrating another embodiment ofa document authenticator and discriminator according to the presentinvention;

FIG. 58a is a functional block diagram illustrating another embodimentof a document authenticator and discriminator according to the presentinvention;

FIG. 58b is a functional block diagram illustrating another embodimentof a document authenticator and discriminator according to the presentinvention;

FIG. 58c is a functional block diagram illustrating another embodimentof a document authenticator and discriminator according to the presentinvention;

FIG. 58d is a functional block diagram illustrating another embodimentof a document authenticator and discriminator according to the presentinvention;

FIG. 59 is an enlarged plan view of the control and display panel in themachine of FIG. 1;

FIG. 60a is a side view of one embodiment of a document authenticatingsystem according to the present invention;

FIG. 60b is a top view of the embodiment of FIG. 60a along the direction60 b;

FIG. 60c is a top view of the embodiment of FIG. 60a along the direction60 c;

FIG. 61 is a functional block diagram illustrating one embodiment of adocument authenticating system according to the present invention;

FIGS. 62-67 are enlarged plan views of various embodiments of controlpanels; and

FIG. 68 is an exploded perspective view of a touch screen device.

DETAILED DESCRIPTION OF THE EMBODIMENTS

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

According to one embodiment of the present invention, a currencydiscrimination system adapted to U.S. currency is described inconnection with, for example, FIGS. 1-38. Subsequently, modifications tosuch a discrimination system will be described in obtaining a currencydiscrimination system in accordance with other embodiments of thepresent invention, such a currency discriminator systems having multiplescanheads per side. Furthermore, while the embodiments below entail thescanning of currency bills, the system of the present invention isapplicable to other documents as well. For example, the system of thepresent invention may be employed in conjunction with stockcertificates, bonds, and postage and food stamps.

Referring now to FIGS. 1 and 2a, there is shown one embodiment of acurrency scanning and counting machine 10 according to the presentinvention. The machine 10 includes an input receptacle or bill acceptingstation 12 where stacks of currency bills that need to be identified andcounted are positioned. Bills in the input receptacle are acted upon bya bill separating station 14 which functions to pick out or separate onebill at a time for being sequentially relayed by a bill transportmechanism 16 (FIG. 2a), according to a precisely predetermined transportpath, between a pair of scanheads 18 a, 18 b where the currencydenomination of the bill is scanned and identified. In one embodiment,bills are scanned and identified at a rate in excess of 800 bills perminute. In the embodiment depicted, each scanhead 18 a, 18 b is anoptical scanhead that scans for characteristic information from ascanned bill 17 which is used to identify the denomination of the bill.The scanned bill 17 is then transported to an output receptacle or billstacking station 20 where bills so processed are stacked for subsequentremoval.

Each optical scanhead 18 a, 18 b preferably comprises a pair of lightsources 22 directing light onto the bill transport path so as toilluminate a substantially rectangular light strip 24 upon a currencybill 17 positioned on the transport path adjacent the scanhead 18. Lightreflected off the illuminated strip 24 is sensed by a photodetector 26positioned between the two light sources. The analog output of thephotodetector 26 is converted into a digital signal by means of ananalog-to-digital (ADC) convertor unit 28 whose output is fed as adigital input to a central processing unit (CPU) 30.

While scanheads 18 a, 18 b of FIG. 2a are optical scanheads, it shouldbe understood that it may be designed to detect a variety ofcharacteristic information from currency bills. Additionally, thescanhead may employ a variety of detection means such as magnetic,optical, electrical conductivity, and capacitive sensors. Use of suchsensors is discussed in more detail below (see e.g., FIG. 2d).

Referring again to FIG. 2a, the bill transport path is defined in such away that the transport mechanism 16 moves currency bills with the narrowdimension of the bills being parallel to the transport path and the scandirection. Alternatively, the system 10 may be designed to scan billsalong their long dimension or along a skewed dimension. As a bill 17traverses the scanheads 18 a, 18 b, the coherent light strip 24effectively scans the bill across the narrow dimension of the bill. Inthe embodiment depicted, the transport path is so arranged that acurrency bill 17 is scanned across a central section of the bill alongits narrow dimension, as shown in FIG. 2a. Each scanhead functions todetect light reflected from the bill as it moves across the illuminatedlight strip 24 and to provide an analog representation of the variationin reflected light, which, in turn, represents the variation in the darkand light content of the printed pattern or indicia on the surface ofthe bill. This variation in light reflected from the narrow dimensionscanning of the bills serves as a measure for distinguishing, with ahigh degree of confidence, among a plurality of currency denominationswhich the system is programmed to handle.

A series of such detected reflectance signals are obtained across thenarrow dimension of the bill, or across a selected segment thereof, andthe resulting analog signals are digitized under control of the CPU 30to yield a fixed number of digital reflectance data samples. The datasamples are then subjected to a normalizing routine for processing thesampled data for improved correlation and for smoothing out variationsdue to “contrast” fluctuations in the printed pattern existing on thebill surface. The normalized reflectance data represents acharacteristic pattern that is unique for a given bill denomination andprovides sufficient distinguishing features among characteristicpatterns for different currency denominations.

In order to ensure strict correspondence between reflectance samplesobtained by narrow dimension scanning of successive bills, thereflectance sampling process is preferably controlled through the CPU 30by means of an optical encoder 32 which is linked to the bill transportmechanism 16 and precisely tracks the physical movement of the bill 17between the scanheads 18 a, 18 b. More specifically, the optical encoder32 is linked to the rotary motion of the drive motor which generates themovement imparted to the bill along the transport path. In addition, themechanics of the feed mechanism ensure that positive contact ismaintained between the bill and the transport path, particularly whenthe bill is being scanned by the scanheads. Under these conditions, theoptical encoder 32 is capable of precisely tracking the movement of thebill 17 relative to the light strips 24 generated by the scanheads 18 a,18 b by monitoring the rotary motion of the drive motor.

The outputs of the photodetectors 26 are monitored by the CPU 30 toinitially detect the presence of the bill adjacent the scanheads and,subsequently, to detect the starting point of the printed pattern on thebill, as represented by the thin borderline 17 a which typicallyencloses the printed indicia on currency bills. Once the borderline 17 ahas been detected, the optical encoder 32 is used to control the timingand number of reflectance samples that are obtained from the outputs ofthe photodetectors 26 as the bill 17 moves across the scanheads.

FIG. 2b illustrates one embodiment of a currency scanning and countingmachine 10 similar to that of FIG. 2a but having a scanhead on only asingle side of the transport path.

FIG. 2c illustrates one embodiment of a currency scanning and countingmachine 10 similar to that of FIG. 2b but illustrating feeding andscanning of bills along their wide direction.

As illustrated in FIGS. 2b-2 c, the transport mechanism 16 movescurrency bills with a preselected one of their two dimensions (narrow orwide) being parallel to the transport path and the scan direction. FIGS.2b and 4 a illustrate bills oriented with their narrow dimension “W”parallel to the direction of movement and scanning while FIGS. 2c and 4b illustrate bills oriented with their wide dimension “L” parallel tothe direction of movement and scanning.

Referring now to FIG. 2d, there is shown a functional block diagramillustrating one embodiment of a currency discriminating andauthenticating system according to the present invention. The operationof the system of FIG. 2d is the same as that of FIG. 2a except asmodified below. The system 10 includes a bill accepting station 12 wherestacks of currency bills that need to be identified, authenticated, andcounted are positioned. Accepted bills are acted upon by a billseparating station 14 which functions to pick out or separate one billat a time for being sequentially relayed by a bill transport mechanism16, according to a precisely predetermined transport path, across twoscanheads 18 and 39 where the currency denomination of the bill isidentified and the genuineness of the bill is authenticated. In theembodiment depicted, scanhead 18 is an optical scanhead that scans for afirst type of characteristic information from a scanned bill 17 which isused to identify the bill's denomination. A second scanhead 39 scans fora second type of characteristic information from the scanned bill 17.While in the illustrated embodiment scanheads 18 and 39 are separate anddistinct, it is understood that these may be incorporated into a singlescanhead. For example, where the first characteristic sensed isintensity of reflected light and the second characteristic sensed iscolor, a single optical scanhead having a plurality of detectors, one ormore without filters and one or more with colored filters, may beemployed (U.S. Pat. No. 4,992,860 incorporated herein by reference). Thescanned bill is then transported to a bill stacking station 20 wherebills so processed are stacked for subsequent removal.

The optical scanhead 18 of the embodiment depicted in FIG. 2d comprisesat least one light source 22 directing a beam of coherent lightdownwardly onto the bill transport path so as to illuminate asubstantially rectangular light strip 24 upon a currency bill 17positioned on the transport path below the scanhead 18. Light reflectedoff the illuminated strip 24 is sensed by a photodetector 26 positioneddirectly above the strip. The analog output of photodetector 26 isconverted into a digital signal by means of an analog-to-digital (ADC)convertor unit 28 whose output is fed as a digital input to a centralprocessing unit (CPU) 30.

The second scanhead 39 comprises at least one detector 41 for sensing asecond type of characteristic information from a bill. The analog outputof the detector 41 is converted into a digital signal by means of asecond analog to digital converter 43 whose output is also fed as adigital input to the central processing unit (CPU) 30.

While scanhead 18 in the embodiment of FIG. 2d is an optical scanhead,it should be understood that the first and second scanheads 18 and 39may be designed to detect a variety of characteristic information fromcurrency bills. Additionally these scanheads may employ a variety ofdetection means such as magnetic or optical sensors. For example, avariety of currency characteristics can be measured using magneticsensing. These include detection of patterns of changes in magnetic flux(U.S. Pat. No. 3,280,974), patterns of vertical grid lines in theportrait area of bills (U.S. Pat. No. 3,870,629), the presence of asecurity thread (U.S. Pat. No. 5,151,607), total amount of magnetizablematerial of a bill (U.S. Pat. No. 4,617,458), patterns from sensing thestrength of magnetic fields along a bill (U.S. Pat. No. 4,593,184), andother patterns and counts from scanning different portions of the billsuch as the area in which the denomination is written out (U.S. Pat. No.4,356,473).

With regards to optical sensing, a variety of currency characteristicscan be measured such as detection of density (U.S. Pat. No. 4,381,447),color (U.S. Pat. Nos. 4,490,846; 3,496,370; 3,480,785), length andthickness (U.S. Pat. No. 4,255,651), the presence of a security thread(U.S. Pat. No. 5,151,607) and holes (U.S. Pat. No. 4,381,447), and otherpatterns of reflectance and transmission (U.S. Pat. Nos. 3,496,370;3,679,314; 3,870,629; 4,179,685). Color detection techniques may employcolor filters, colored lamps, and/or dichroic beamsplitters (U.S. Pat.Nos. 4,841,358; 4,658,289; 4,716,456; 4,825,246, 4,992,860 and EP325,364).

In addition to magnetic and optical sensing, other techniques ofdetecting characteristic information of currency include electricalconductivity sensing, capacitive sensing (U.S. Pat. No. 5,122,754[watermark, security thread]; U.S. Pat. No. 3,764,899 [thickness]; U.S.Pat. No. 3,815,021 [dielectric properties]; U.S. Pat. No. 5,151,607[security thread]), and mechanical sensing (U.S. Pat. No. 4,381,447[limpness]; U.S. Pat. No. 4,255,651 [thickness]).

According to one embodiment, the detection of the borderline 17 aconstitutes an important step and realizes improved discriminationefficiency in systems designed to accommodate U.S. currency since theborderline 17 a serves as an absolute reference point for initiation ofsampling. If the edge of a bill were to be used as a reference point,relative displacement of sampling points can occur because of the randommanner in which the distance from the edge to the borderline 17 a variesfrom bill to bill due to the relatively large range of tolerancespermitted during printing and cutting of currency bills. As a result, itbecomes difficult to establish direct correspondence between samplepoints in successive bill scans and the discrimination efficiency isadversely affected. Accordingly, the modified pattern generation methodof the present invention (to be discussed below) is especially importantin discrimination systems designed to accommodate bills other than U.S.currency because many non-U.S. bills lack a borderline around theprinted indicia on their bills. Likewise, the modified patterngeneration method of the present invention is especially important indiscrimination systems designed to accommodate bills other than U.S.currency because the printed indicia of many non-U.S. bills lack sharplydefined edges which in turns inhibits using the edge of the printedindicia of a bill as a trigger for the initiation of the scanningprocess and instead promotes reliance on using the edge of the billitself as the trigger for the initiation of the scanning process.

The use of the optical encoder 32 for controlling the sampling processrelative to the physical movement of a bill 17 across the scanheads 18a, 18 b is also advantageous in that the encoder 32 can be used toprovide a predetermined delay following detection of the borderline 17 aprior to initiation of samples. The encoder delay can be adjusted insuch a way that the bill 17 is scanned only across those segments whichcontain the most distinguishable printed indicia relative to thedifferent currency denominations.

In the case of U.S. currency, for instance, it has been determined thatthe central, approximately two-inch (approximately 5 cm) portion ofcurrency bills, as scanned across the central section of the narrowdimension of the bill, provides sufficient data for distinguishing amongthe various U.S. currency denominations. Accordingly, the opticalencoder can be used to control the scanning process so that reflectancesamples are taken for a set period of time and only after a certainperiod of time has elapsed after the borderline 17 a is detected,thereby restricting the scanning to the desired central portion of thenarrow dimension of the bill.

FIGS. 3-5b illustrate the scanning process in more detail. Referring toFIG. 4a, as a bill 17 is advanced in a direction parallel to the narrowedges of the bill, scanning via a slit in the scanhead 18 a or 18 b iseffected along a segment S of the central portion of the bill 17. Thissegment S begins a fixed distance D inboard of the borderline 17 a. Asthe bill 17 traverses the scanhead, a strip s of the segment S is alwaysilluminated, and the photodetector 26 produces a continuous outputsignal which is proportional to the intensity of the light reflectedfrom the illuminated strip s at any given instant. This output issampled at intervals controlled by the encoder, so that the samplingintervals are precisely synchronized with the movement of the billacross the scanhead. FIG. 4b is similar to FIG. 4a but illustratingscanning along the wide dimension of the bill 17.

As illustrated in FIGS. 3, 5 a, and 5 b, it is preferred that thesampling intervals be selected so that the strips s that are illuminatedfor successive samples overlap one another. The odd-numbered andeven-numbered sample strips have been separated in FIGS. 3, 5 a, and 5 bto more clearly illustrate this overlap. For example, the first andsecond strips s1 and s2 overlap each other, the second and third stripss2 and s3 overlap each other, and so on. Each adjacent pair of stripsoverlap each other. In the illustrative example, this is accomplished bysampling strips that are 0.050 inch (0.127 cm) wide at 0.029 inch (0.074cm) intervals, along a segment S that is 1.83 inch (4.65 cm) long (64samples).

FIGS. 6a and 6 b illustrate two opposing surfaces of U.S. bills. Theprinted pattern on the black and green surfaces of the bill are eachenclosed by respective thin borderlines B₁ and B₂. As a bill is advancedin a direction parallel to the narrow edges of the bill, scanning viathe wide slit of one of the scanheads is effected along a segment S_(A)of the central portion of the black surface of the bill (FIG. 6a). Aspreviously stated, the orientation of the bill along the transport pathdetermines whether the upper or lower scanhead scans the black surfaceof the bill. This segment S_(A) begins a fixed distance D₁ inboard ofthe borderline B₁, which is located a distance W₁ from the edge of thebill. The scanning along segment S_(A) is as describe in connection withFIGS. 3, 4 a, and 5 a.

Similarly, the other of the two scanheads scans a segment S_(B) of thecentral portion of the green surface of the bill (FIG. 6b). Theorientation of the bill along the transport path determines whether theupper or lower scanhead scans the green surface of the bill. Thissegment S_(B) begins a fixed distance D₂ inboard of the border line B₂,which is located a distance W₂ from the edge of the bill. For U.S.currency, the distance W₂ on the green surface is greater than thedistance W₁ on the black surface. It is this feature of U.S. currencywhich permits one to determine the orientation of the bill relative tothe upper and lower scanheads 18, thereby permitting one to select onlythe data samples corresponding to the green surface for correlation tothe master characteristic patterns in the EPROM 34. The scanning alongsegment S_(B) is as describe in connection with FIGS. 3, 4 a, and 5 a.

FIGS. 6c and 6 d are side elevations of FIG. 2a according to oneembodiment of the present invention. FIG. 6c shows the first surface ofa bill scanned by an upper scanhead and the second surface of the billscanned by a lower scanhead while FIG. 6d shows the first surface of abill scanned by a lower scanhead and the second surface of the billscanned by an upper scanhead. FIGS. 6c and 6 d illustrate the pair ofoptical scanheads 18 a, 18 b are disposed on opposite sides of thetransport path to permit optical scanning of both opposing surfaces of abill. With respect to United States currency, these opposing surfacescorrespond to the black and green surfaces of a bill. One of the opticalscanheads 18 (the “upper” scanhead 18 a in FIGS. 6c-6 d) is positionedabove the transport path and illuminates a light strip upon a firstsurface of the bill, while the other of the optical scanheads 18 (the“lower” scanhead 18 b in FIGS. 6c-6 d) is positioned below the transportpath and illuminates a light strip upon the second surface of the bill.The surface of the bill scanned by each scanhead 18 is determined by theorientation of the bill relative to the scanheads 18. The upper scanhead18 a is located slightly upstream relative to the lower scanhead 18 b.

The photodetector of the upper scanhead 18 a produces a first analogoutput corresponding to the first surface of the bill, while thephotodetector of the lower scanhead 18 b produces a second analog outputcorresponding to the second surface of the bill. The first and secondanalog outputs are converted into respective first and second digitaloutputs by means of respective analog-to-digital (ADC) convertor units28 whose outputs are fed as digital inputs to a central processing unit(CPU) 30. As described in detail below, the CPU 30 uses the sequence ofoperations illustrated in FIG. 12 to determine which of the first andsecond digital outputs corresponds to the green surface of the bill, andthen selects the “green” digital output for subsequent correlation to aseries of master characteristic patterns stored in EPROM 34. Accordingto one embodiment, as explained below, the master characteristicpatterns are generated by performing scans on the green surfaces, notblack surfaces, of bills of different denominations. According to oneembodiment, the analog output corresponding to the black surface of thebill is not used for subsequent correlation.

The optical sensing and correlation technique is based upon using theabove process to generate a series of stored intensity signal patternsusing genuine bills for each denomination of currency that is to bedetected. According to one embodiment, two or four sets of masterintensity signal samples are generated and stored within the systemmemory, preferably in the form of an EPROM 34 (see FIG. 2a), for eachdetectable currency denomination. According to one embodiment these aresets of master green-surface intensity signal samples. In the case ofU.S. currency, the sets of master intensity signal samples for each billare generated from optical scans, performed on the green surface of thebill and taken along both the “forward” and “reverse” directionsrelative to the pattern printed on the bill. Alternatively, the opticalscanning may be performed on the black side of U.S. currency bills or oneither surface of foreign bills. Additionally, the optical scanning maybe performed on both sides of a bill.

In adapting this technique to U.S. currency, for example, sets of storedintensity signal samples are generated and stored for seven differentdenominations of U.S. currency, i.e., $1, $2, $5, $10, $20, $50 and$100. For bills which produce significant pattern changes when shiftedslightly to the left or right, such as the $2, the $10 and/or the $100bills in U.S. currency, it is preferred to store two green-side patternsfor each of the “forward” and “reverse” directions, each pair ofpatterns for the same direction represent two scan areas that areslightly displaced from each other along the long dimension of the bill.Accordingly, a set of 16 [or 18] different green-side mastercharacteristic patterns are stored within the EPROM for subsequentcorrelation purposes (four master patterns for the $10 bill [or fourmaster patterns for the $10 bill and the $2 bill and/or the $100 bill]and two master patterns for each of the other denominations). Thegeneration of the master patterns is discussed in more below. Once themaster patterns have been stored, the pattern generated by scanning abill under test is compared by the CPU 30 with each of the 16 [or 18]master patterns of stored intensity signal samples to generate, for eachcomparison, a correlation number representing the extent of correlation,i.e., similarity between corresponding ones of the plurality of datasamples, for the sets of data being compared.

According to one embodiment, in addition to the above set of 18 originalgreen-side master patterns, five more sets of green-side master patternsare stored in memory. These sets are explained more fully in conjunctionwith FIGS. 18a and 18 b below.

The CPU 30 is programmed to identify the denomination of the scannedbill as corresponding to the set of stored intensity signal samples forwhich the correlation number resulting from pattern comparison is foundto be the highest. In order to preclude the possibility ofmischaracterizing the denomination of a scanned bill, as well as toreduce the possibility of spurious notes being identified as belongingto a valid denomination, a bi-level threshold of correlation is used asthe basis for making a “positive” call. If a “positive” call can not bemade for a scanned bill, an error signal is generated.

According to one embodiment, master patterns are also stored forselected denominations corresponding to scans along the black side ofU.S. bills. More particularly, according to one embodiment, multipleblack-side master patterns are stored for $20, $50 and $100 bills. Foreach of these denominations, three master patterns are stored for scansin the forward and reverse directions for a total of six patterns foreach denomination. For a given scan direction, black-side masterpatterns are generated by scanning a corresponding denominated billalong a segment located about the center of the narrow dimension of thebill, a segment slightly displaced (0.2 inches) to the left of center,and a segment slightly displaced (0.2 inches) to the right of center.When the scanned pattern generated from the green side of a test billfails to sufficiently correlate with one of the green-side masterpatterns, the scanned pattern generated from the black side of a testbill is then compared to black-side master patterns in some situationsas described in more detail below in conjunction with FIGS. 19a-19 c.

Using the above sensing and correlation approach, the CPU 30 isprogrammed to count the number of bills belonging to a particularcurrency denomination as part of a given set of bills that have beenscanned for a given scan batch, and to determine the aggregate total ofthe currency amount represented by the bills scanned during a scanbatch. The CPU 30 is also linked to an output unit 36 (FIG. 2a and FIG.2b) which is adapted to provide a display of the number of billscounted, the breakdown of the bills in terms of currency denomination,and the aggregate total of the currency value represented by countedbills. The output unit 36 can also be adapted to provide a print-out ofthe displayed information in a desired format.

Referring again to the embodiment depicted in FIG. 2d, as a result ofthe first comparison described above based on the reflected lightintensity information retrieved by scanhead 18, the CPU 30 will haveeither determined the denomination of the scanned bill 17 or determinedthat the first scanned signal samples fail to sufficiently correlatewith any of the sets of stored intensity signal samples in which case anerror is generated. Provided that an error has not been generated as aresult of this first comparison based on reflected light intensitycharacteristics, a second comparison is performed. This secondcomparison is performed based on a second type of characteristicinformation, such as alternate reflected light properties, similarreflected light properties at alternate locations of a bill, lighttransmissivity properties, various magnetic properties of a bill, thepresence of a security thread embedded within a bill, the color of abill, the thickness or other dimension of a bill, etc. The second typeof characteristic information is retrieved from a scanned bill by thesecond scanhead 39. The scanning and processing by scanhead 39 may becontrolled in a manner similar to that described above with regard toscanhead 18.

In addition to the sets of stored first characteristic information, inthis example stored intensity signal samples, the EPROM 34 stores setsof stored second characteristic information for genuine bills of thedifferent denominations which the system 10 is capable of handling.Based on the denomination indicated by the first comparison, the CPU 30retrieves the set or sets of stored second characteristic data for agenuine bill of the denomination so indicated and compares the retrievedinformation with the scanned second characteristic information. Ifsufficient correlation exists between the retrieved information and thescanned information, the CPU 30 verifies the genuineness of the scannedbill 17. Otherwise, the CPU generates an error. While the embodimentillustrated in FIG. 2d depicts a single CPU 30 for making comparisons offirst and second characteristic information and a single EPROM 34 forstoring first and second characteristic information, it is understoodthat two or more CPUs and/or EPROMs could be used, including one CPU formaking first characteristic information comparisons and a second CPU formaking second characteristic information comparisons. Using the abovesensing and correlation approach, the CPU 30 is programmed to count thenumber of bills belonging to a particular currency denomination whosegenuineness has been verified as part of a given set of bills that havebeen scanned for a given scan batch, and to determine the aggregatetotal of the currency amount represented by the bills scanned during ascan batch.

Referring now to FIGS. 7a and 7 b, there is shown a representation, inblock diagram form, of one circuit arrangement for processing andcorrelating reflectance data according to the system of this invention.The CPU 30 accepts and processes a variety of input signals includingthose from the optical encoder 32, the sensor 26 and the erasableprogrammable read only memory (EPROM) 60. The EPROM 60 has stored withinit the correlation program on the basis of which patterns are generatedand test patterns compared with stored master programs in order toidentify the denomination of test currency. A crystal 40 serves as thetime base for the CPU 30, which is also provided with an externalreference voltage VREF 42 on the basis of which peak detection of sensedreflectance data is performed.

According to one embodiment, the CPU 30 also accepts a timer resetsignal from a reset unit 44 which, as shown in FIG. 7b, accepts theoutput voltage from the photodetector 26 and compares it, by means of athreshold detector 44 a, relative to a pre-set voltage threshold,typically 5.0 volts, to provide a reset signal which goes “high” when areflectance value corresponding to the presence of paper is sensed. Morespecifically, reflectance sampling is based on the premise that noportion of the illuminated light strip (24 in FIG. 2a) is reflected tothe photodetector in the absence of a bill positioned below thescanhead. Under these conditions, the output of the photodetectorrepresents a “dark” or “zero” level reading. The photodetector outputchanges to a “white” reading, typically set to have a value of about 5.0volts, when the edge of a bill first becomes positioned below thescanhead and falls under the light strip 24. When this occurs, the resetunit 44 provides a “high” signal to the CPU 30 and marks the initiationof the scanning procedure.

The machine-direction dimension, that is, the dimension parallel to thedirection of bill movement, of the illuminated strip of light producedby the light sources within the scanhead is set to be relatively smallfor the initial stage of the scan when the thin borderline is beingdetected, according to one embodiment. The use of the narrow slitincreases the sensitivity with which the reflected light is detected andallows minute variations in the “gray” level reflected off the billsurface to be sensed. This is important in ensuring that the thinborderline of the pattern, i.e., the starting point of the printedpattern on the bill, is accurately detected. Once the borderline hasbeen detected, subsequent reflectance sampling is performed on the basisof a relatively wider light strip in order to completely scan across thenarrow dimension of the bill and obtain the desired number of samples,at a rapid rate. The use of a wider slit for the actual sampling alsosmooths out the output characteristics of the photodetector and realizesthe relatively large magnitude of analog voltage which is essential foraccurate representation and processing of the detected reflectancevalues.

The CPU 30 processes the output of the sensor 26 through a peak detector50 which essentially functions to sample the sensor output voltage andhold the highest, i.e., peak, voltage value encountered after thedetector has been enabled. For U.S. currency, the peak detector is alsoadapted to define a scaled voltage on the basis of which the printedborderline on the currency bills is detected. The output of the peakdetector 50 is fed to a voltage divider 54 which lowers the peak voltagedown to a scaled voltage V_(s) representing a predefined percentage ofthis peak value. The voltage V_(s) is based upon the percentage drop inoutput voltage of the peak detector as it reflects the transition fromthe “high” reflectance value resulting from the scanning of theunprinted edge portions of a currency bill to the relatively lower“gray” reflectance value resulting when the thin borderline isencountered. Preferably, the scaled voltage V_(s) is set to be about70-80 percent of the peak voltage.

The scaled voltage V_(s) is supplied to a line detector 56 which is alsoprovided with the incoming instantaneous output of the sensor 26. Theline detector 56 compares the two voltages at its input side andgenerates a signal L_(DET) which normally stays “low” and goes “high”when the edge of the bill is scanned. The signal L_(DET) goes “low” whenthe incoming sensor output reaches the pre-defined percentage of thepeak output up to that point, as represented by the voltage V_(S). Thus,when the signal L_(DET) goes “low”, it is an indication that theborderline of the bill pattern has been detected. At this point, the CPU30 initiates the actual reflectance sampling under control of theencoder 32 and the desired fixed number of reflectance samples areobtained as the currency bill moves across the illuminated light stripand is scanned along the central section of its narrow dimension.

When master characteristic patterns are being generated, the reflectancesamples resulting from the scanning of one or more genuine bills foreach denomination are loaded into corresponding designated sectionswithin a system memory 60, which is preferably an EPROM. During currencydiscrimination, the reflectance values resulting from the scanning of atest bill are sequentially compared, under control of the correlationprogram stored within the EPROM 60, with the corresponding mastercharacteristic patterns stored within the EPROM 60. A pattern averagingprocedure for scanning bills and generating characteristic patterns isdescribed below in connection with FIGS. 15a-15 e.

In addition to the optical scanheads, the bill-scanning system (e.g.,FIGS. 2a-2 d) preferably includes a magnetic scanhead. A variety ofcurrency characteristics can be measured using magnetic scanning. Theseinclude detection of patterns of changes in magnetic flux (U.S. Pat. No.3,280,974), patterns of vertical grid lines in the portrait area ofbills (U.S. Pat. No. 3,870,629), the presence of a security thread (U.S.Pat. No. 5,151,607), total amount of magnetizable material of a bill(U.S. Pat. No. 4,617,458), patterns from sensing the strength ofmagnetic fields along a bill (U.S. Pat. No. 4,593,184), and otherpatterns and counts from scanning different portions of the bill such asthe area in which the denomination is written out (U.S. Pat. No.4,356,473).

The interrelation between the use of the first and second type ofcharacteristic information can be seen by considering FIGS. 8a and 8 bwhich comprise a flowchart illustrating the sequence of operationsinvolved in implementing a discrimination and authentication systemaccording to one embodiment of the present invention. Upon theinitiation of the sequence of operations (step 1748), reflected lightintensity information is retrieved from a bill being scanned (step1750). Similarly, second characteristic information is also retrievedfrom the bill being scanned (step 1752). Denomination error and secondcharacteristic error flags are cleared (steps 1753 and 1754).

Next the scanned intensity information is compared to each set of storedintensity information corresponding to genuine bills of alldenominations the system is programmed to accommodate (step 1758). Foreach denomination, a correlation umber is calculated. The system then,based on the correlation numbers calculated, determines either thedenomination of the scanned bill or generates a denomination error bysetting the denomination error flag steps 1760 and 1762). In the casewhere the denomination error flag is set (step 1762), the process isended (step 1772). Alternatively, if based on this first comparison, thesystem is able to determine the denomination of the scanned bill, thesystem proceeds to compare the scanned second characteristic informationwith the stored second characteristic information corresponding to thedenomination determined by the first comparison (step 1764).

For example, if as a result of the first comparison the scanned bill isdetermined to be a $20 bill, the scanned second characteristicinformation is compared to the stored second characteristic informationcorresponding to a genuine $20 bill. In this manner, the system need notmake comparisons with stored second characteristic information for theother denominations the system is programmed to accommodate. If based onthis second comparison (step 1764) it is determined that the scannedsecond characteristic information does not sufficiently match that ofthe stored second characteristic information (step 1766), then a secondcharacteristic error is generated by setting the second characteristicerror flag (step 1768) and the process is ended (step 1772). If thesecond comparison results in a sufficient match between the scanned andstored second characteristic information (step 1766), then thedenomination of the scanned bill is indicated (step 1770) and theprocess is ended (step 1772).

An example of an interrelationship between authentication based on afirst and second characteristic can be seen by considering Table 1. Thedenomination determined by optical scanning of a bill may be used tofacilitate authentication of the bill by magnetic scanning, using therelationship set forth in Table 1.

TABLE 1 Sensitivity Denomination 1 2 3 4 5 $1 200 250 300 375 450 $2 100125 150 225 300 $5 200 250 300 350 400 $10 100 125 150 200 250 $20 120150 180 270 360 $50 200 250 300 375 450 $100 100 125 150 250 350

Table 1 depicts relative total magnetic content thresholds for variousdenominations of genuine bills. Columns 1-5 represent varying degrees ofsensitivity selectable by a user of a device employing the presentinvention. The values in Table 1 are set based on the scanning ofgenuine bills of varying denominations for total magnetic content andsetting required thresholds based on the degree of sensitivity selected.The information in Table 1 is based on the total magnetic content of agenuine $1 being 1000. The following discussion is based on asensitivity setting of 4. In this example it is assumed that magneticcontent represents the second characteristic tested. If the comparisonof first characteristic information, such as reflected light intensity,from a scanned billed and stored information corresponding to genuinebills results in an indication that the scanned bill is a $10denomination, then the total magnetic content of the scanned bill iscompared to the total magnetic content threshold of a genuine $10 bill,i.e., 200. If the magnetic content of the scanned bill is less than 200,the bill is rejected. Otherwise it is accepted as a $10 bill.

In order to avoid problems associated with re-feeding bills, countingbills by hand, and adding together separate totals, according to oneembodiment of the present invention a number of selection elementsassociated with individual denominations are provided. In FIG. 1, theseselection elements are in the form of keys or buttons of a keypad. Othertypes of selection elements such as switches or displayed keys in atouch-screen environment may be employed. The operation of the selectionelements and several of the operating modes of the discriminator 10 aredescribed below in conjunction with FIGS. 56 and 59.

Referring now to FIGS. 9-11b, there are shown flow charts illustratingthe sequence of operations involved in implementing the above-describedoptical sensing and correlation technique. FIGS. 9 and 10, inparticular, illustrate the sequences involved in detecting the presenceof a bill adjacent the scanheads and the borderlines on each side of thebill. Turning to FIG. 9, at step 70, the lower scanhead fine lineinterrupt is initiated upon the detection of the fine line by the lowerscanhead. An encoder counter is maintained that is incremented for eachencoder pulse. The encoder counter scrolls from 0-65,535 and then startsat 0 again. At step 71 the value of the encoder counter is stored inmemory upon the detection of the fine line by the lower scanhead. Atstep 72 the lower scanhead fine line interrupt is disabled so that itwill not be triggered again during the interrupt period. At step 73, itis determined whether the magnetic sampling has been completed for theprevious bill. If it has not, the magnetic total for the previous billis stored in memory at step 74 and the magnetic sampling done flag isset at step 75 so that magnetic sampling of the present bill maythereafter be performed. Steps 74 and 75 are skipped if it is determinedat step 73 that the magnetic sampling has been completed for theprevious bill. At step 76, a lower scanhead bit in the trigger flag isset. This bit is used to indicate that the lower scanhead has detectedthe fine line. The magnetic sampler is initialized at step 77 and themagnetic sampling interrupt is enabled at step 78. A density sampler isinitialized at step 79 and a density sampling interrupt is enabled atstep 80. The lower read data sampler is initialized at step 81 and alower scanhead data sampling interrupt is enabled at step 82. At step83, the lower scanhead fine line interrupt flag is reset and at step 84the program returns from the interrupt.

Turning to FIG. 10, at step 85, the upper scanhead fine line interruptis initiated upon the detection of the fine line by the upper scanhead.At step 86 the value of the encoder counter is stored in memory upon thedetection of the fine line by the upper scanhead. This information inconnection with the encoder counter value associated with the detectionof the fine line by the lower scanhead may then be used to determine theface orientation of a bill, that is whether a bill is fed green side upor green side down in the case of U.S. bills as is described in moredetail below in connection with FIG. 12. At step 87 the upper scanheadfine line interrupt is disabled so that it will not be triggered againduring the interrupt period. At step 88, the upper scanhead bit in thetrigger flag is set. This bit is used to indicate that the upperscanhead has detected the fine line. By checking the lower and upperscanhead bits in the trigger flag it can be determined whether each sidehas detected a respective fine line. Next, the upper scanhead datasampler is initialized at step 89 and the upper scanhead data samplinginterrupt is enabled at step 90. At step 91, the upper scanhead fineline interrupt flag is reset and at step 92 the program returns from theinterrupt.

Referring now to FIGS. 11a and 11 b there are shown, respectively, thedigitizing routines associated with the lower and upper scanheads. FIG.11a is a flow chart illustrating the sequential procedure involved inthe analog-to-digital conversion routine associated with the lowerscanhead. The routine is started at step 93 a. Next, the sample pointeris decremented at step 94 a so as to maintain an indication of thenumber of samples remaining to be obtained. The sample pointer providesan indication of the sample being obtained and digitized at a giventime. At step 95 a, the digital data corresponding to the output of thephotodetector associated with the lower scanhead for the current sampleis read. The data is converted to its final form at step 96 a and storedwithin a pre-defined memory segment as X_(IN-L) at step 97 a.

Next, at step 98 a, a check is made to see if the desired fixed numberof samples “N” has been taken. If the answer is found to be negative,step 99 a is accessed where the interrupt authorizing the digitizationof the succeeding sample is enabled and the program returns frominterrupt at step 100 a for completing the rest of the digitizingprocess. However, if the answer at step 98 a is found to be positive,i.e., the desired number of samples have already been obtained, a flag,namely the lower scanhead done flag bit, indicating the same is set atstep 101 a and the program returns from interrupt at step 102 a.

FIG. 11b is a flow chart illustrating the sequential procedure involvedin the analog-to-digital conversion routine associated with the upperscanhead. The routine is started at step 93 b. Next, the sample pointeris decremented at step 94 b so as to maintain an indication of thenumber of samples remaining to be obtained. The sample pointer providesan indication of the sample being obtained and digitized at a giventime. At step 95 b, the digital data corresponding to the output of thephotodetector associated with the upper scanhead for the current sampleis read. The data is converted to its final form at step 96 b and storedwithin a pre-defined memory segment as X_(IN-U) at step 97 b.

Next, at step 98 b, a check is made to see if the desired fixed numberof samples “N” has been taken. If the answer is found to be negative,step 99 b is accessed where the interrupt authorizing the digitizationof the succeeding sample is enabled and the program returns frominterrupt at step 100 b for completing the rest of the digitizingprocess. However, if the answer at step 98 b is found to be positive.i.e., the desired number of samples have already been obtained, a flag,namely the upper scanhead done flag bit, indicating the same is set atstep 101 b and the program returns from interrupt at step 102 b.

The CPU 30 is programmed with the sequence of operations in FIG. 12 tocorrelate at least initially only the test pattern corresponding to thegreen surface of a scanned bill. As shown in FIGS. 6c-6 d, the upperscanhead 18 a is located slightly upstream adjacent the bill transportpath relative to the lower scanhead 18 b. The distance between thescanheads 18 a, 18 b in a direction parallel to the transport pathcorresponds to a predetermined number of encoder counts. It should beunderstood that the encoder 32 produces a repetitive tracking signalsynchronized with incremental movements of the bill transport mechanism,and this repetitive tracking signal has a repetitive sequence of counts(e.g., 65,535 counts) associated therewith. As a bill is scanned by theupper and lower scanheads 18 a, 18 b. the CPU 30 monitors the output ofthe upper scanhead 18 a to detect the borderline of a first bill surfacefacing the upper scanhead 18 a. Once this borderline of the firstsurface is detected, the CPU 30 retrieves and stores a first encodercount in memory. Similarly, the CPU 30 monitors the output of the lowerscanhead 18 b to detect the borderline of a second bill surface facingthe lower scanhead 18 b. Once the borderline of the second surface isdetected, the CPU 30 retrieves and stores a second encoder count inmemory.

Referring to FIG. 12, the CPU 30 is programmed to calculate thedifference between the first and second encoder counts (step 105 a). Ifthis difference is greater than the predetermined number of encodercounts corresponding to the distance between the scanheads 18 a, 18 bplus some safety factor number “X”, e.g., 20 (step 106), the bill isoriented with its black surface facing the upper scanhead 18 a and itsgreen surface facing the lower scanhead 18 b. This can best beunderstood by reference to FIG. 6c which shows a bill with the foregoingorientation. In this situation, once the borderline B₁ of the blacksurface passes beneath the upper scanhead 18 a and the first encodercount is stored, the borderline B₂ still must travel for a distancegreater than the distance between the upper and lower scanheads 18 a, 18b in order to pass over the lower scanhead 18 b. As a result, thedifference between the second encoder count associated with theborderline B₂ and the first encoder count associated with the borderlineB₁ will be greater than the predetermined number of encoder countscorresponding to the distance between the scanheads 18 a, 18 b. With thebill oriented with its green surface facing the lower scanhead, the CPU30 sets a flag to indicate that the test pattern produced by the lowerscanhead 18 b should be correlated (step 107). Next, this test patternis correlated with the green-side master characteristic patterns storedin memory (step 109).

If at step 106 the difference between the first and second encodercounts is less than the predetermined number of encoder countscorresponding to the distance between the scanheads 18 a, 18 b, the CPU30 is programmed to determine whether the difference between the firstand second encoder counts is less than the predetermined number minussome safety number “X”, e.g., 20 (step 108). If the answer is negative,the orientation of the bill relative to the scanheads 18 a, 18 b isuncertain so the CPU 30 is programmed to correlate the test patternsproduced by both the upper and lower scanheads 18 a, 18 b with thegreen-side master characteristic patterns stored in memory (steps 109,110, and 111).

If the answer is affirmative, the bill is oriented with its greensurface facing the upper scanhead 18 a and its black surface facing thelower scanhead 18 b. This can best be understood by reference to FIG.6d, which shows a bill with the foregoing orientation. In thissituation, once the borderline B₂ of the green surface passes beneaththe upper scanhead 18 a and the first encoder count is stored, theborderline B₁ must travel for a distance less than the distance betweenthe upper and lower scanheads 18 a, 18 b in order to pass over the lowerscanhead 18 b. As a result, the difference between the second encodercount associated with the borderline B₁ and the first encoder countassociated with the borderline B₂ should be less than the predeterminednumber of encoder counts corresponding to the distance between thescanheads 18 a, 18 b. To be on the safe side, it is required that thedifference between first and second encoder counts be less than thepredetermined number minus the safety number “X”. Therefore, the CPU 30is programmed to correlate the test pattern produced by the upperscanhead 18 a with the green-side master characteristic patterns storedin memory (step 111).

After correlating the test pattern associated with either the upperscanhead 18 a, the lower scanhead 18 b, or both scanheads 18 a, 18 b,the CPU 30 is programmed to perform the bi-level threshold check (step112).

A simple correlation procedure is utilized for processing digitizedreflectance values into a form which is conveniently and accuratelycompared to corresponding values pre-stored in an identical format. Morespecifically, as a first step, the mean value {overscore (X)} for theset of digitized reflectance samples (comparing “n” samples) obtainedfor a bill scan run is first obtained as below: $\begin{matrix}{\overset{\_}{X} = {\sum\limits_{i = 0}^{n}\frac{X_{i}}{n}}} & (1)\end{matrix}$

Subsequently, a normalizing factor Sigma (“σ”) is determined as beingequivalent to the sum of the square of the difference between eachsample and the mean, as normalized by the total number n of samples.More specifically, the normalizing factor is calculated as below:$\begin{matrix}{\sigma = {\sum\limits_{i = 0}^{n}\frac{{{X_{i} - \overset{\_}{X}}}^{2}}{n}}} & (2)\end{matrix}$

In the final step, each reflectance sample is normalized by obtainingthe difference between the sample and the above-calculated mean valueand dividing it by the square root of the normalizing factor or asdefined by the following equation: $\begin{matrix}{X_{n} = \frac{X_{i} - \overset{\_}{X}}{(\sigma)^{½}}} & (3)\end{matrix}$

The result of using the above correlation equations is that, subsequentto the normalizing process, a relationship of correlation exists betweena test pattern and a master pattern such that the aggregate sum of theproducts of corresponding samples in a test pattern and any masterpattern, when divided by the total number of samples, equals unity ifthe patterns are identical. Otherwise, a value less than unity isobtained. Accordingly, the correlation number or factor resulting fromthe comparison of normalized samples within a test pattern to those of astored master pattern provides a clear indication of the degree ofsimilarity or correlation between the two patterns.

According to one embodiment of this invention, the fixed number ofreflectance samples which are digitized and normalized for a bill scanis selected to be 64. It has experimentally been found that the use ofhigher binary orders of samples (such as 128, 256, etc.) does notprovide a correspondingly increased discrimination efficiency relativeto the increased processing time involved in implementing theabove-described correlation procedure. It has also been found that theuse of a binary order of samples lower than 64, such as 32, produces asubstantial drop in discrimination efficiency.

The correlation factor can be represented conveniently in binary termsfor ease of correlation. In one embodiment, for instance, the factor ofunity which results when a hundred percent correlation exists isrepresented in terms of the binary number 2¹⁰, which is equal to adecimal value of 1024. Using the above procedure, the normalized sampleswithin a test pattern are compared to the master characteristic patternsstored within the system memory in order to determine the particularstored pattern to which the test pattern corresponds most closely byidentifying the comparison which yields a correlation number closest to1024.

A bi-level threshold of correlation is required to be satisfied before aparticular call is made, for at least certain denominations of bills.More specifically, the correlation procedure is adapted to identify thetwo highest correlation numbers resulting from the comparison of thetest pattern to one of the stored patterns. At that point, a minimumthreshold of correlation is required to be satisfied by these twocorrelation numbers. It has experimentally been found that a correlationnumber of about 850 serves as a good cut-off threshold above whichpositive calls may be made with a high degree of confidence and belowwhich the designation of a test pattern as corresponding to any of thestored patterns is uncertain. As a second threshold level, a minimumseparation is prescribed between the two highest correlation numbersbefore making a call. This ensures that a positive call is made onlywhen a test pattern does not correspond, within a given range ofcorrelation, to more than one stored master pattern. Preferably, theminimum separation between correlation numbers is set to be 150 when thehighest correlation number is between 800 and 850. When the highestcorrelation number is below 800, no call is made.

The procedure involved in comparing test patterns to master patterns isdiscussed below in connection with FIG. 18a.

Next a routine designated as “CORRES” is initiated. The procedureinvolved in executing the routine CORRES is illustrated at FIG. 13 whichshows the routine as starting at step 114. Step 115 determines whetherthe bill has been identified as a $2 bill, and, if the answer isnegative, step 116 determines whether the best correlation number (“call#1”) is greater than 799. If the answer is negative, the correlationnumber is too low to identify the denomination of the bill withcertainty, and thus step 117 generates a “no call” code. A “no callprevious bill” flag is then set at step 118, and the routine returns tothe main program at step 119.

An affirmative answer at step 116 advances the system to step 120, whichdetermines whether the sample data passes an ink stain test (describedbelow). If the answer is negative, a “no call” code is generated at step117. If the answer is affirmative, the system advances to step 121 whichdetermines whether the best correlation number is greater than 849. Anaffirmative answer at step 121 indicates that the correlation number issufficiently high that the denomination of the scanned bill can beidentified with certainty without any further checking. Consequently, a“denomination” code identifying the denomination represented by thestored pattern resulting in the highest correlation number is generatedat step 122, and the system returns to the main program at step 119.

A negative answer at step 121 indicates that the correlation number isbetween 800 and 850. It has been found that correlation numbers withinthis range are sufficient to identify all bills except the $2 bill.Accordingly, a negative response at step 121 advances the system to step123 which determines whether the difference between the two highestcorrelation numbers (“call #1” and “call #2”) is greater than 149. Ifthe answer is affirmative, the denomination identified by the highestcorrelation number is acceptable, and thus the “denomination” code isgenerated at step 122. If the difference between the two highestcorrelation numbers is less than 150, step 123 produces a negativeresponse which advances the system to step 117 to generate a “no call”code.

Returning to step 115, an affirmative response at this step indicatesthat the initial call is a $2 bill. This affirmative response initiatesa series of steps 124-127 which are identical to steps 116, 120, 121 and123 described above, except that the numbers 799 and 849 used in steps116 and 121 are changed to 849 and 899, respectively, in steps 124 and126. The result is either the generation of a “no call” code at step 117or the generation of a $2 “denomination” code at step 122.

One problem encountered in currency recognition and counting systems isthe difficulty involved in interrupting (for a variety of reasons) andresuming the scanning and counting procedure as a stack of bills isbeing scanned. If a particular currency recognition unit (CRU) has to behalted in operation due to a “major” system error, such as a bill beingjammed along the transport path, there is generally no concern about theoutstanding transitional status of the overall recognition and countingprocess. However, where the CRU has to be halted due to a “minor” error,such as the identification of a scanned bill as being a counterfeit(based on a variety of monitored parameters) or a “no call” (a billwhich is not identifiable as belonging to a specific currencydenomination based on the plurality of stored master patterns and/orother criteria), it is desirable that the transitional status of theoverall recognition and counting process be retained so that the CRU maybe restarted without any effective disruptions of therecognition/counting process.

More specifically, once a scanned bill has been identified as a “nocall” bill (B₁) based on some set of predefined criteria, it isdesirable that this bill B₁ be transported directly to the systemstacker and the CRU brought to a halt with bill B₁ being the last billdeposited in the output receptacle, while at the same time ensuring thatthe following bills are maintained in positions along the bill transportpath whereby CRU operation can be conveniently resumed without anydisruption of the recognition/counting process.

Since the bill processing speeds at which currency recognition systemsmust operate are substantially high (speeds of the order of 800 to 1500bills per minute), it is practically impossible to totally halt thesystem following a “no call” without the following bill B₂ alreadyoverlapping the optical scanhead and being partially scanned. As aresult, it is virtually impossible for the CRU system to retain thetransitional status of the recognition/counting process (particularlywith respect to bill B₂) in order that the process may be resumed oncethe bad bill B₁ has been transported to the stacker, convenientlyremoved therefrom, and the system restarted. The basic problem is thatif the CRU is halted with bill B₂ only partially scanned, it isdifficult to reference the data reflectance samples extracted therefromin such a way that the scanning may be later continued (when the CRU isrestarted) from exactly the same point where the sample extractionprocess was interrupted when the CRU was stopped.

Even if an attempt were made at immediately halting the CRU systemfollowing a “no call,” any subsequent scanning of bills would be totallyunreliable because of mechanical backlash effects and the resultantdisruption of the optical encoder routine used for bill scanning.Consequently, when the CRU is restarted, the call for the following billis also likely to be bad and the overall recognition/counting process istotally disrupted as a result of an endless loop of “no calls.”

The above problems are solved by the use of a currency detecting andcounting technique whereby a scanned bill identified as a “no call” istransported directly to the top of the system stacker and the CRU ishalted without adversely affecting the data collection and processingsteps for a succeeding bill. Accordingly, when the CRU is restarted, theoverall bill recognition and counting procedure can be resumed withoutany disruption as if he CRU had never been halted at all.

According to one technique, if the bill is identified as a “no call”based on any of a variety of conventionally defined bill criteria, theCRU is subjected to a controlled deceleration process whereby the speedat which bills are moved across the scanhead is reduced from the normaloperating speed. During this deceleration process the “no call” bill(B₁) is transported to the top of the stacker and, at the same time, thefollowing bill B₂ is subjected to the standard scanning procedure inorder to identify the denomination.

The rate of deceleration is such that optical scanning of bill B₂ iscompleted by the time the CRU operating speed is reduced to a predefinedoperating speed. While the exact operating speed at the end of thescanning of bill B₂ is not critical, the objective is to permit completescanning of bill B₂ without subjecting it to backlash effects that wouldresult if the ramping were too fast, while at the same time ensuringthat bill B₁ has in fact been transported to the stacker.

It has been experimentally determined that at nominal operating speedsof the order of 1000 bills per minute, the deceleration is preferablysuch that the CRU operating speed is reduced to about one-fifth of itsnormal operating speed at the end of the deceleration phase, i.e., bythe time optical scanning of bill B₂ has been completed. It has beendetermined that at these speed levels, positive calls can be made as tothe denomination of bill B₂ based on reflectance samples gathered duringthe deceleration phase with a relatively high degree of certainty (i.e.,with a correlation number exceeding about 850).

Once the optical scanning of bill B₂ has been completed, the speed isreduced to an even slower speed until the bill B₂ has passed bill-edgesensors S1 and S2 described below, and the bill B₂ is then brought to acomplete stop. At the same time, the results of the processing ofscanned data corresponding to bill B₂ are stored in system memory. Theultimate result of this stopping procedure is that the CRU is brought toa complete halt following the point where the scanning of bill B₂ hasbeen reliably completed, and the scan procedure is not subjected to thedisruptive effects (backlash, etc.) which would result if a completehalt were attempted immediately after bill B₁ is identified as a “nocall.”

The reduced operating speed of the machine at the end of thedeceleration phase is such that the CRU can be brought to a total haltbefore the next following bill B₃ has been transported over the opticalscanhead. Thus, when the CRU is in fact halted, bill B₁ is positioned atthe top of the system stacker, bill B₂ is maintained in transit betweenthe optical scanhead and the stacker after it has been subjected toscanning, and the following bill B₃ is stopped short of the opticalscanhead.

When the CRU is restarted, presumably after corrective action has beentaken in response to the “minor” error which led to the CRU beingstopped (such as the removal of the “no call” bill from the outputreceptacle), the overall scanning operation can be resumed in anuninterrupted fashion by using the stored call results for bill B₂ asthe basis for updating the system count appropriately, moving bill B₂from its earlier transitional position along the transport path into thestacker, and moving bill B₃ along the transport path into the opticalscanhead area where it can be subjected to normal scanning andprocessing. A routine for executing the deceleration/stopping proceduredescribed above is illustrated by the flow chart in FIG. 14. Thisroutine is initiated at step 170 with the CRU in its normal operatingmode. At step 171, a test bill B₁ is scanned and the data reflectancesamples resulting therefrom are processed. Next, at step 172, adetermination is made as to whether or not test bill B₁ is a “no call”using predefined criteria in combination with the overall billrecognition procedure, such as the routine of FIG. 13. If the answer atstep 172 is negative, i.e., the test bill B₁ can be identified, step 173is accessed where normal bill processing is continued in accordance withthe procedures described above. If, however, the test bill B₁ is foundto be a “no call” at step 172, step 174 is accessed where CRUdeceleration is initiated, e.g., the transport drive motor speed isreduced to about one-fifth its normal speed.

Subsequently, the “no call” bill B₁ is guided to the stacker while, atthe same time, the following test bill B₂ is brought under the opticalscanhead and subjected to the scanning and processing steps. The callresulting from the scanning and processing of bill B₂ is stored insystem memory at this point. Step 175 determines whether the scanning ofbill B₂ is complete. When the answer is negative, step 176 determineswhether a preselected “bill timeout” period has expired so that thesystem does not wait for the scanning of a bill that is not present. Anaffirmative answer at step 176 results in the transport drive motorbeing stopped at step 179 while a negative answer at step 176 causessteps 175 and 176 to be reiterated until one of them produces anaffirmative response.

After the scanning of bill B₂ is complete and before stopping thetransport drive motor, step 178 determines whether either of the sensorsS1 or S2 (described below) is covered by a bill. A negative answer atstep 178 indicates that the bill has cleared both sensors S1 and S2, andthus the transport drive motor is stopped at step 179. This signifiesthe end of the deceleration/stopping process. At this point in time,bill B₂ remains in transit while the following bill B₃ is stopped on thetransport path just short of the optical scanhead.

Following step 179, corrective action responsive to the identificationof a “no call” bill is conveniently undertaken; the top-most bill in thestacker is easily removed therefrom and the CRU is then in condition forresuming the scanning process. Accordingly, the CRU can be restarted andthe stored results corresponding to bill B₂, are used to appropriatelyupdate the system count. Next, the identified bill B₂ is guided alongthe transport path to the stacker, and the CRU continues with its normalprocessing routine. While the above deceleration process has beendescribed in a context of a “no call” error, other minor errors (e.g.,suspect bills, stranger bills in stranger mode, etc.) are handled in thesame manner.

In currency discrimination systems in which discrimination is based onthe comparison of a pattern obtained from scanning a subject bill tostored master patterns corresponding to various denominations, thepatterns which are designated as master patterns significantly influencethe performance characteristics of a discrimination system. For example,in the system described in U.S. Pat. No. 5,295,196, the correlationprocedure and the accuracy with which a denomination is identifieddirectly relates to the degree of correspondence between reflectancesamples on the test pattern and corresponding samples on the storedmaster patterns. In other systems, master patterns have been produced byscanning a genuine bill for a given denomination and storing theresulting pattern as the master pattern for that denomination. However,due to variations among genuine bills, this method is likely to resultin poor performance of the discrimination system by rejecting anunacceptable number of genuine bills. It has been found that therelative crispness, age, shrinkage, usage, and other characteristics ofa genuine bill can effect the resulting pattern generated by scanning.These factors are often interrelated. For example, it has been foundthat currency bills which have experienced a high degree of usageexhibit a reduction in both the narrow and wide dimensions of the bills.This shrinkage of “used” bills which, in turn, causes correspondingreductions in their narrow dimensions, can possibly produce a drop inthe degree of correlation between such used bills of a givendenomination and the corresponding master patterns.

As a result, a discrimination system which generates a master patternbased on a single scan of a genuine bill is not likely to performsatisfactorily. For example, if the $20 master pattern is generated byscanning a crisp, genuine $20 bill, the discrimination system may rejectan unacceptable number of genuine but worn $20 bills. Likewise, if the$20 master pattern is generated using a very worn, genuine $20 bill, thediscrimination system may reject an unacceptable number of genuine butcrisp $20 bills.

According to one embodiment of the present invention, a master patternfor a given denomination is generated by averaging a plurality ofcomponent patterns. Each component pattern is generated by scanning agenuine bill of the given denomination.

According to a first method, master patterns are generated by scanning astandard bill a plurality of times, typically three (3) times, andobtaining the average of corresponding data samples before storing theaverage as representing a master pattern. In other words, a masterpattern for a given denomination is generated by averaging a pluralityof component patterns, wherein all of the component patterns aregenerated by scanning a single genuine bill of “standard” quality of thegiven denomination. The “standard” bill is a slightly used bill, asopposed to a crisp new bill or one which has been subject to a highdegree of usage. Rather, the standard bill is a bill of good to averagequality. Component patterns generated according to this first methodsare illustrated in FIGS. 15a-15 c. More specifically, FIGS. 15a-15 cshow three test patterns generated, respectively, for the forwardscanning of a $1 bill along its green side, the reverse scanning of a $2bill on its green side, and the forward scanning of a $100 bill on itsgreen side. It should be noted that, for purposes of clarity the testpatterns in FIGS. 15a-15 c were generated by using 128 reflectancesamples per bill scan, as opposed to the preferred use of only 64samples. The marked difference existing among corresponding samples forthese three test patterns is indicative of the high degree of confidencewith which currency denominations may be called using the foregoingoptical sensing and correlation procedure.

According to a second method, a master pattern for a given denominationis generated by scanning two or more standard bills of standard qualityand obtaining a plurality of component patterns. These componentpatterns are then averaged in deriving a master pattern. For example, ithas been found that some genuine $5 bills have dark stairs on theLincoln Memorial while other genuine $5 bills have light stairs. Tocompensate for this variation, standard bills for which componentpatterns are derived may be chosen with at least one standard billscanned having dark stairs and with at least one standard bill havinglight stairs.

It has been found that an alternate method can lead to improvedperformance in a discrimination systems, especially with regards tocertain denominations. For example, it has been found that the printedindicia on a $10 bill has changed slightly with 1990 series billsincorporating security threads. More specifically, 1990 series $10 billshave a borderline-to-borderline dimension which is slightly greater thanprevious series $10 bills. Likewise it has been found that the scannedpattern of an old, semi-shrunken $5 bill can differ significantly fromthe scanned pattern of a new $5 bill.

According to a third method, a master pattern for a given denominationis generated by averaging a plurality of component patterns, whereinsome of the component patterns are generated by scanning one or more newbills of the given denomination and some of the component patterns aregenerated by scanning one or more old bills of the given denomination.New bills are bills of good quality which have been printed in recentyears and have a security thread incorporated therein (for thosedenominations in which security threads are placed). New bills arepreferably relatively crisp. A new $10 bill is preferably a 1990 seriesor later bill of very high quality, meaning that the bill is in nearmint condition. Old bills are bills exhibiting some shrinkage and oftensome discoloration. Shrinkage may result from a bill having beensubjected to a relatively high degree of use. A new bill utilized inthis third method is of higher quality than a standard bill of theprevious methods, while an old bill in this third method is of lowerquality than a standard bill.

The third method can be understood by considering Table 2 whichsummarizes the manner in which component patterns are generated for avariety of denominations.

TABLE 2 Component Scans by Denomination Denomination Scan Direction CP1CP2 CP3 $1 Forward −0.2 std 0.0 std +0.2 std $1 Reverse −0.2 std 0.0 std+0.2 std $2, left Forward −0.2 std −0.15 std −0.1 std $2, left Reverse−0.2 std −0.15 std −0.1 std $2, right Forward 0.0 std +0.1 std +0.2 std$2, right Reverse 0.0 std +0.1 std +0.2 std $5 Forward −0.2 old 0.0 new+0.2 old (lt str) (dk str) (lt str) $5 Reverse −0.2 old 0.0 new +0.2 old(lt Str) (dk str) (lt str) $10, left Forward −0.2 old −0.1 new 0.0 old$10, left Reverse 0.0 old +0.1 new +0.2 old $10, right Forward +0.1 old+0.2 new +0.3 old $10, right Reverse −0.2 old −0.15 new −0.1 old $20Forward −0.2 old 0.0 new +0.2 old $20 Reverse −0.2 old 0.0 new +0.2 old$50 Forward −0.2 std 0.0 std +0.2 std $50 Reverse −0.2 std 0.0 std +0.2std $100 Forward −0.2 std 0.0 std +0.2 std $100 Reverse −0.2 std 0.0 std+0.2 std

Table 2 summarizes the position of the scanhead relative to the centerof the green surface of United States currency as well as the type ofbill to be scanned for generating component patterns for variousdenominations. The three component patterns (“CP”) for a givendenomination and for a given scan direction are averaged to yield acorresponding master pattern. The eighteen (18) rows correspond to themethod of storing eighteen (18) master patterns. The scanhead positionis indicated relative to the center of the borderlined area of the bill.Thus a position of “0.0” indicates that the scanhead is centered overthe center of the borderlined area of the bill. Displacements to theleft of center are indicated by negative numbers, while displacements tothe right are indicated by positive numbers. Thus a position of “−0.2”indicates a displacement of {fraction (2/10)}ths of an inch to the leftof the center of a bill, while a position of “+0.1” indicates adisplacement of {fraction (1/10)}ths of an inch to the right of thecenter of a bill.

Accordingly, Table 2 indicates that component patterns for a $20 billscanned in the forward direction are obtained by scanning an old $20bill {fraction (2/10)}ths of a inch to the right and to the left of thecenter of the bill and by scanning a new $20 bill directly down thecenter of the bill. FIG. 15d is a graph illustrating these threepatterns. These three patterns are then averaged to obtain the masterpattern for a $20 bill scanned in the forward direction. FIG. 15e is agraph illustrating an pattern for a $20 bill scanned in the forwarddirection derived by averaging the patterns of FIG. 15d. This patternbecomes the corresponding $20 master pattern after undergoingnormalization. In generating the master patterns, one may use a scanningdevice in which a bill to be scanned is held stationary and a scanheadis moved over the bill. Such a device permits the scanhead to be movedlaterally, left and right, over a bill to be scanned and thus permitsthe scanhead to be positioned over the area of the bill which one wishesto scan, for example, {fraction (2/10)}ths of inch to the left of thecenter of the borderlined area.

As discussed above, for $10 bills two patterns are obtained in each scandirection with one pattern being scanned slightly to the left of thecenter and one pattern being scanned slightly to the right of thecenter. For $5 bills, it has been found that some $5 bills are printedwith darker stairs (“dk str”) on the picture of the Lincoln Memorialwhile others are printed with lighter stairs (“It str”). The effect ofthis variance is averaged out by using an old bill having light stairsand a new bill having dark stairs.

As can be seen from Table 2, for some bills, the third method of usingold and new bills is not used; rather, a standard (“std”) bill is usedfor generating all three component patterns as with the first method.Thus, the master pattern for a $1 bill scanned in the forward directionis obtained by averaging three component patterns generated by scanninga standard bill three times, once {fraction (2/10)}ths of an inch to theleft, once down the center, and once {fraction (2/10)}ths of an inch tothe right.

As illustrated by Table 2, a discrimination system may employ acombination of the developed methods of this invention wherein, forexample, some master patterns are generated according the first methodand some master patterns are generated according to the third method.Likewise, a discrimination system may combine the scanning of new,standard, and old bills to generate component patterns to be averaged inobtaining a master pattern. Additionally, a discrimination system maygenerate master patterns by scanning bills of various qualities and/orhaving various characteristics and then averaging the resultantpatterns. Alternatively, a discrimination system may scan multiple billsof a given quality for a given denomination, e.g., three new $50 bills,while scanning one or more bills of a different quality for a differentdenomination, e.g., three old and worn $1 bills, to generate componentpatterns to be averaged in obtaining master patterns.

The optical sensing and correlation technique described above permitsidentification of pre-programmed currency denominations with a highdegree of accuracy and is based upon a relatively low processing timefor digitizing sampled reflectance values and comparing them to themaster characteristic patterns. The approach is used to scan currencybills, normalize the scanned data and generate master patterns in such away that bill scans during operation have a direct correspondencebetween compared sample points in portions of the bills which possessthe most distinguishable printed indicia. A relatively low number ofreflectance samples is required in order to be able to adequatelydistinguish among several currency denominations.

An advantage with this approach is that it is not required that currencybills be scanned along their wide dimensions. Further, the reduction inthe number of samples reduces the processing time to such an extent thatadditional comparisons can be made during the time available between thescanning of successive bills. More specifically, as described above, itbecomes possible to compare a test pattern with multiple stored mastercharacteristic patterns so that the system is made capable ofidentifying currency which is scanned in the “forward” or “reverse”directions along the green surface of the bill.

Another advantage accruing from the reduction in processing timerealized by the sensing and correlation scheme is that the response timeinvolved in either stopping the transport of a bill that has beenidentified as “spurious”, i.e., not corresponding to any of the storedmaster characteristic patterns, or diverting such a bill to a separatestacker bin, is correspondingly shortened. Accordingly, the system canconveniently be programmed to set a flag when a scanned pattern does notcorrespond to any of the master patterns. The identification of such acondition can be used to stop the bill transport drive motor for themechanism. Since the optical encoder is tied to the rotational movementof the drive motor, synchronism can be maintained between pre- andpost-stop conditions.

The correlation procedure and the accuracy with which a denomination isidentified directly relates to the degree of correspondence betweenreflectance samples on the test pattern and corresponding samples on thestored master patterns. Thus, shrinkage of “used” bills which, in turn,causes corresponding reductions in both their narrow and widedimensions, can possibly produce a drop in the degree of correlationbetween such used bills of a given denomination and the correspondingmaster patterns. Currency bills which have experienced a high degree ofusage exhibit such a reduction in both the narrow and wide dimensions ofthe bills. While the illustrated sensing and correlation techniqueremains relatively independent of any changes in the non-preselecteddimension of bills, reduction along the preselected dimension can affectcorrelation factors by realizing a relative displacement of reflectancesamples obtained as the “shrunk” bills are transported across thescanhead. Thus, if the bills are transported and scanned along theirwide dimension, the sensing and correlation technique will remainrelatively independent of any changes in the narrow dimension of billsand reduction along the wide dimension can affect correlation factors.Similarly, if the bills are transported and scanned along their narrowdimension, the sensing and correlation technique will remain relativelyindependent of any changes in the wide dimension of bills and reductionalong the narrow dimension can affect correlation factors.

In order to accommodate or nullify the effect of such bill shrinking,the above-described correlation technique can be modified by use of aprogressive shifting approach whereby a test pattern which does notcorrespond to any of the master patterns is partitioned into predefinedsections, and samples in successive sections are progressively shiftedand compared again to the stored patterns in order to identify thedenomination. It has experimentally been determined that suchprogressive shifting effectively counteracts any sample displacementresulting from shrinkage of a bill along the preselected dimension.

The progressive shifting effect is best illustrated by the correlationpatterns shown in FIGS. 16a-e. For purposes of clarity, the illustratedpatterns were generated using 128 samples for each bill scan as comparedto the preferred use of 64 samples. FIG. 16a shows the correlationbetween a test pattern (represented by a heavy line) and a correspondingmaster pattern (represented by a thin line). It is clear from FIG. 16athat the degree of correlation between the two patterns is relativelylow and exhibits a correlation factor of 606.

The manner in which the correlation between these patterns is increasedby employing progressive shifting is best illustrated by considering thecorrelation at the reference points designated as A-E along the axisdefining the number of samples. The effect on correlation produced by“single” progressive shifting is shown in FIG. 16b which shows “single”shifting of the test pattern of FIG. 16a. This is effected by dividingthe test pattern into two equal segments each comprising 64 samples. Thefirst segment is retained without any shift, whereas the second segmentis shifted by a factor of one data sample. Under these conditions, it isfound that the correlation factor at the reference points located in theshifted section, particularly at point E, is improved.

FIG. 16c shows the effect produced by “double” progressive shiftingwhereby sections of the test pattern are shifted in three stages. Thisis accomplished by dividing the overall pattern into three approximatelyequal sized sections. Section one is not shifted, section two is shiftedby one data sample (as in FIG. 16b), and section three is shifted by afactor of two data samples. With “double” shifting, it can be seen thatthe correlation factor at point E is further increased.

On a similar basis, FIG. 16d shows the effect on correlation produced by“triple” progressive shifting where the overall pattern is first dividedinto four (4) approximately equal sized sections. Subsequently, sectionone is retained without any shift, section two is shifted by one datasample, section three is shifted by two data samples, and section fouris shifted by three data samples. Under these conditions, thecorrelation factor at point E is seen to have increased again.

FIG. 16e shows the effect on correlation produced by “quadruple”shifting, where the pattern is first divided into five (5) approximatelyequal sized sections. The first four (4) sections are shifted inaccordance with the “triple” shifting approach of FIG. 16d, whereas thefifth section is shifted by a factor of four (4) data samples. From FIG.16e it is clear that the correlation at point E is increased almost tothe point of superimposition of the compared data samples.

In an alternative progressive shifting approach, the degree of shrinkageof a scanned bill is determined by comparing the length of the scannedbill, as measured by the scanhead, with the length of an “unshrunk”bill. This “unshrunk” length is pre-stored in the system memory. Thetype of progressive shifting, e.g., “single”, “double”, “triple”, etc.,applied to the test pattern is then directly based upon the measureddegree of shrinkage. The greater the degree of shrinkage, the greaterthe number of sections into which the test pattern is divided. Anadvantage of this approach is that only one correlation factor iscalculated, as opposed to potentially calculating several correlationfactors for different types of progressive shifting.

In yet another progressive shifting approach, instead of applyingprogressive shifting to the test pattern, progressive shifting isapplied to each of the master patterns. The master patterns in thesystem memory are partitioned into predefined sections, and samples insuccessive sections are progressively shifted and compared again to thescanned test pattern in order to identify the denomination. To reducethe amount of processing time, the degree of progressive shifting whichshould be applied to the master patterns may be determined by firstmeasuring the degree of shrinkage of the scanned bill. By firstmeasuring the degree of shrinkage, only one type of progressive shiftingis applied to the stored master patterns.

Instead of rearranging the scanned test pattern or the stored masterpatterns, the system memory may contain pre-stored patternscorresponding to various types of progressive shifting. The scanned testpattern is then compared to all of these stored patterns in the systemmemory. However, to reduce the time required for processing the data,this approach may be modified to first measure the degree of shrinkageand to then select only those stored patterns from the system memorywhich correspond to the measure degree of shrinkage for comparison withthe scanned test pattern.

The advantage of using the progressive shifting approach, as opposed tomerely shifting by a set amount of data samples across the overall testpattern, is that the improvement in correlation achieved in the initialsections of the pattern as a result of shifting is not neutralized oroffset by any subsequent shifts in the test pattern. It is apparent fromthe above figures that the degree of correlation for sample pointsfalling within the progressively shifted sections increasescorrespondingly.

More importantly, the progressive shifting realizes substantialincreases in the overall correlation factor resulting from patterncomparison. For instance, the original correlation factor of 606 (FIG.16a) is increased to 681 by the “single” shifting shown in FIG. 16b. The“double” shifting shown in FIG. 16c increases the correlation number to793, the “triple” shifting of FIG. 16d increases the correlation numberto 906, and, finally, the “quadruple” shifting shown in FIG. 16eincreases the overall correlation number to 960. Using the aboveapproach, it has been determined that used currency bills which exhibita high degree of shrinkage and which cannot be accurately identified asbelonging to the correct currency denomination when the correlation isperformed without any shifting, can be identified with a high degree ofcertainty by using progressive shifting approach, preferably by adopting“triple” or “quadruple” shifting.

In currency discrimination systems in which discrimination is based onthe comparison of a pattern obtained from scanning a subject bill tostored master patterns corresponding to various denominations, thepatterns which are compared to each other significantly influence theperformance characteristics of a discrimination system. For example, inthe system described in U.S. Pat. No. 5,295,196, the correlationprocedure and the accuracy with which a denomination is identifieddirectly relates to the degree of correspondence between reflectancesamples on the test pattern and corresponding samples on the storedmaster patterns. In accordance with method described above, the identityof a bill under test is determined by comparing a scanned patterngenerated by scanning the bill under test with one or more masterpatterns associated with genuine bills. If the scanned patternsufficiently correlates to one of the master pattern, the identity ofthe bill may be called. The process of identifying a bill under test maybe subjected to a bi-level threshold test as described above.

However, the degree of correlation between a scanned and a masterpattern may be negatively impacted if the two patterns are not properlyaligned with each other. Such misalignment between patterns may in turnnegatively impact upon the performance of a currency identificationsystem. Misalignment between patterns may result from a number offactors. For example, if a system is designed so that the scanningprocess is initiated in response to the detection of the thin borderlinesurrounding U.S. currency or the detection of some other printed indiciasuch as the edge of printed indicia on a bill, stray marks may causeinitiation of the scanning process at an improper time. This isespecially true for stray marks in the area between the edge of a billand the edge of the printed indicia on the bill. Such stray marks maycause the scanning process to be initiated too soon, resulting in ascanned pattern which leads a corresponding master pattern.Alternatively, where the detection of the edge of a bill is used totrigger the scanning process, misalignment between patterns may resultfrom variances between the location of printed indicia on a billrelative to the edges of a bill. Such variances may result fromtolerances permitted during the printing and/or cutting processes in themanufacture of currency. For example, it has been found that location ofthe leading edge of printed indicia on Canadian currency relative to theedge of Canadian currency may vary up to approximately 0.2 inches(approximately 0.5 cm).

According to one embodiment of the present invention, the problemsassociated with misaligned patterns are overcome by employing animproved method of generating multiple scanned and/or master patternsand comparing the multiple scanned and master patterns with each other.Briefly, one embodiment of the improved pattern generation methodinvolves removing data samples from one end of a pattern to be modifiedand adding data values on the opposite end equal to the data valuescontained in the corresponding sequence positions of the pattern towhich the modified pattern is to be compared. This process may berepeated, up to a predetermined number of times, until a sufficientlyhigh correlation is obtained between the two patterns so as to permitthe identity of a bill under test to be called.

One embodiment of the present invention can be further understood byconsidering Table 3. Table 3 contains data samples generated by scanningthe narrow dimension of Canadian $2 bills along a segment positionedabout the center of the bill on the side opposite the portrait side.More specifically, the second column of Table 3 represents a scannedpattern generated by scanning a test Canadian $2 bill. The scannedpattern comprises 64 data samples arranged in a sequence. Each datasample has a sequence position, 1-64, associated therewith. The fifthcolumn represents a master pattern associated with a Canadian $2 bill.The master pattern likewise comprises a sequence of 64 data samples. Thethird and fourth columns represent the scanned pattern after it has beenmodified in the forward direction one and two times, respectively. Inthe embodiment depicted in Table 3, one data sample is removed from thebeginning of the preceding pattern during each modification.

TABLE 3 Sequence Scanned Scanned Pattern Scanned Pattern Master PositionPattern Modified Once Modified Twice Pattern 1 93 50 −21 161 2 50 −21 50100 3 −21 50 93 171 4 50 93 65 191 5 93 65 22 252 6 65 22 79 433 7 22 79136 312 8 79 136 193 434 9 136 193 278 90 10 193 278 164 0 11 278 164136 20 12 164 136 278 444 . . . . . . . . . . . . . . . 52 −490 −518−447 −1090 53 −518 −447 −646 −767 54 −447 −646 −348 −575 55 −646 −348−92 −514 56 −348 −92 −63 −545 57 −92 −63 −205 −40 58 −63 −205 605 166559 −205 605 1756 1705 60 605 1756 1401 1685 61 1756 1401 1671 2160 621401 1671 2154 2271 63 1671 2154 *2240 2240 64 2154 *2210 *2210 2210

The modified pattern represented in the third column is generated byadding an additional data value to the end of the original scannedpattern sequence which effectively removes the first data sample of theoriginal pattern, e.g., 93, from the modified pattern. The added datavalue in the last sequence position, 64, is set equal to data valuecontained in the 64th sequence position of the master pattern, e.g.,2210. This copying of the 64th data sample is indicated by an asteriskin the third column. The second modified pattern represented in thefourth column is generated by adding two additional data values to theend of the original scanned pattern which effectively removes the firsttwo data samples of the original scanned, e.g., 93 and 50, from thesecond modified pattern. The last two sequence positions, 63 and 64, arefilled with the data value contained in the 63rd and 64th sequencepositions of the master pattern, e.g., 2240 and 2210, respectively. Thecopying of the 63rd and 64th data samples is indicated by asterisks inthe fourth column.

In the example of Table 3, the printed area of the bill under test fromwhich the scanned pattern was generated was farther away from theleading edge of the bill than was the printed area of the bill fromwhich the master pattern was generated. As a result, the scanned patterntrailed the master pattern. The embodiment of the pattern generationmethod described in conjunction with Table 3 compensates for thevariance of the distance between the edge of the bill and the edge ofthe printed indicia by modifying the scanned pattern in the forwarddirection. As a result of the modification method employed, thecorrelation between the original and modified versions of the scannedpattern and the master pattern increased from 705 for the original,unmodified scanned pattern to 855 for the first modified pattern and to988 for the second modified pattern. Accordingly, the bill under testwhich would otherwise have been rejected may now be properly called as agenuine $2 Canadian bill through the employment of the patterngeneration method discussed above.

Another embodiment of the present invention can be understood withreference to the flowchart of FIGS. 17a-17 c. The process of FIGS.17a-17 c involves a method of identifying a bill under test by comparinga scanned pattern retrieved from a bill under test with one or moremaster patterns associated with one or more genuine bills. After theprocess begins at step 128 a, the scanned pattern is compared with oneor more master patterns associated with genuine bills (step 128 b). Atstep 129 it is determined whether the bill under test can be identifiedbased on the comparison at step 128 b. This may be accomplished byevaluating the correlation between the scanned pattern and each of themaster patterns. If the bill can be identified, the process is ended atstep 130. Otherwise, one or more of the master patterns are designatedfor further processing at step 131. For example, all of the masterpatterns may be designated for further processing. Alternatively, lessthan all of the master patterns may be designated based on a preliminaryassessment about the identity of the bill under test. For example, onlythe master patterns which had the four highest correlation values withrespect to the scanned pattern at step 128 b might be chosen for furtherprocessing. In any case, the number of master patterns designated forfurther processing is M1.

At step 132, either the scanned pattern is designated for modificationor the M1 master patterns designated at step 131 are designated formodification. In one embodiment of the present invention, the scannedpattern is designated for modification and the master patterns remainunmodified. At step 133, it is designated whether forward modificationor reverse modification is to be performed. This determination may bemade, for example, by analyzing the beginning or ending data samples ofthe scanned pattern to determine whether the scanned pattern trails orleads the master patterns.

At step 134, the iteration counter, I, is set equal to one. Theiteration counter is used to keep track of how many times the workingpatterns have been modified. Then at step 135, the number of incrementaldata samples, R, to be removed during each iteration is set. Forexample, in one embodiment of the present invention, only one additionaldata sample is removed from each working pattern during each iterationin which case R is set equal to one.

At step 136, it is determined whether the scanned pattern has beendesignated for modification. If it has, then the scanned pattern isreplicated M1 times and the M1 replicated patterns, one for each of theM1 master patterns, are designated as working patterns at step 137. Ifthe scanned pattern has not been designated for modification, then theM1 master patterns have been so designated, and the M1 master patternsare replicated and designated as working patterns at step 138.Regardless of which pattern or patterns were designated formodification, at step 139, it is determined whether forward or reversemodification is to be performed on the working patterns.

If forward modification is to be performed, the first R×I data samplesfrom each working pattern are removed at step 140. The first R×I datasamples may either be explicitly removed from the working patterns or beremoved as a result of adding additional data samples (step 141) to theend of the pattern and designating the beginning of the modified patternto be the R×I+1 sequence position of the original pattern. As a resultof the modification, the data sample which was in the 64th sequenceposition in the original working pattern will be in the 64−(R×I)sequence position. The added data values in the last R×I sequencepositions of a working pattern are copied from the data samples in thelast R×I sequence positions of a corresponding non-designated pattern atstep 141. After the above described modification, the working patternsare compared with either respective ones of the non-designated patterns(scanned pattern modified/M1 master patterns not designated formodification) or the non-designated pattern (M1 master patternsdesignated for modification/scanned pattern not designated formodification) at step 142.

Alternatively, if reverse modification is to be performed, the last R×Idata samples from each working pattern are removed at step 143. The lastR×I data samples may either be explicitly removed from the workingpatterns or be removed as a result of adding additional data samples(step 144) to the beginning of the pattern and designating the beginningof the modified pattern to start with the added data samples. As aresult of the modification, the data sample which was in the 1stsequence position in the original working pattern will be in the (R×I)+1sequence position. The added data samples in first R×I sequencepositions of a working pattern are copied from the data samples in thefirst R×I sequence positions of a corresponding non-designated patternat step 144. After the above described modification, the workingpatterns are compared with either respective ones of the non-designatedpatterns (scanned pattern modified/M1 master patterns not designated formodification) or the non-designated pattern (M1 master patternsdesignated for modification/scanned pattern not designated formodification) at step 142.

For example, if the scanned pattern is designated for forwardmodification and four master patterns are designated for furtherprocessing, four working patterns are generated from the scanned patternat step 137, one for each of the four master patterns. If R is set totwo at step 135, during the first iteration the last two data samplesfrom each of the M1 master patterns are copied and added to the end ofthe M1 working patterns so as to become the last two sequence positionsof the M1 working patterns, one working pattern being associated witheach of the M1 master patterns. As a result, after the first iteration,four different working patterns are generated with each working patterncorresponding to a modified version of the scanned pattern but with eachhaving data values in its last two sequence positions copied from thelast two sequence positions of a respective one of the M1 masterpatterns. After a second iteration, the last four sequence positions ofeach of the M1 master patterns are copied and added to the end of the M1working patterns so as to become the last four sequence positions of arespective one of the M1 working patterns.

As another example, if four master patterns are designated for furtherprocessing and the four designated master patterns are designated forforward modification, four working patterns are generated at step 138,one from each of the four designated master patterns. If R is set to twoat step 135, during the first iteration the last two data samples of thescanned pattern are copied and added to the end of the M1 workingpatterns so as to become the last two sequence positions of the M1working patterns, one working pattern being associated with each of theM1 master patterns. As a result, after the first iteration, fourdifferent working patterns are generated with each working patterncorresponding to a modified version of a corresponding master patternbut with each having data values in its last two sequence positioncopied from the last two sequence positions of the scanned pattern.After a second iteration, the last four sequence positions of thescanned pattern are copied and added to the end of the M1 workingpatterns so as to become the last four sequence positions of the M1working patterns.

After the comparison at step 142, it is determined whether the billunder test can be identified at step 145. If the bill can be identifiedthe process is ended at step 146. Otherwise, the iteration counter, I,is incremented by one (step 147) and the incremented iteration counteris compared to a maximum iteration number, T (step 148). If theiteration counter, I, is greater than the maximum iteration number, T,then a no call is issued (step 149 a), meaning that a match sufficientto identify the bill under test was not obtained, and the process isended (step 149 b). Otherwise, if the iteration is not greater than themaximum iteration number, the modification process is repeated beginningwith step 136.

The flowchart of FIGS. 17a-17 c is intended to illustrate one embodimentof the present invention. However, it is recognized that there arenumerous ways in which the steps of the flowchart of FIGS. 17a-17 c maybe rearranged or altered and yet still result in the comparison of thesame patterns as would be compared if the steps of FIGS. 17a-17 c werefollowed exactly. For example, instead of generating multiple workingpatterns, a single working pattern may be generated and the leading ortrailing sequence positions successively altered before comparisons tocorresponding non-designated patterns. Likewise, instead of generatingmultiple modified patterns directly from unmodified patterns, multiplemodified patterns may be generated from the preceding modified patterns.For example, instead of generating a twice forward modified scannedpattern by removing the first two data samples from the original scannedpattern and copying the last 2R sequence positions of a correspondingmaster pattern and adding these data values to the end of the originalscanned pattern, the first data sample of the single forward modifiedscanned pattern may be removed and one data sample added to the end ofthe single modified scanned pattern and then the data samples in thelast two sequence positions may be set equal to the data samples in thelast 2R sequence positions of a corresponding master pattern.

In an alternate embodiment of the present invention, instead of copyingdata values from a scanned pattern into corresponding sequence positionsof modified master patterns, leading or trailing sequence positions ofmodified master patterns are filled with zeros.

In an alternate embodiment of the present invention, modified masterpatterns are stored, for example in EPROM 60 of FIG. 7a, before a billunder test is scanned. In such an embodiment, a scanned patternretrieved from a bill under test is compared to the modified masterpatterns stored in memory. Modified master patterns are generated bymodifying a corresponding master pattern in either the forward orbackward direction, or both, and filling in any trailing or leadingsequence positions with zeros. An advantage of such one embodiment isthat no modification needs to be performed during the normal operationof an identification device incorporating such an embodiment.

An example of a procedure involved in comparing test patterns to masterpatterns is illustrated at FIG. 18a which shows the routine as startingat step 150 a. At step 151 a, the best and second best correlationresults (referred to in FIG. 18a as the “#1 and #2 answers”) areinitialized to zero and, at step 152 a, the test pattern is comparedwith each of the sixteen or eighteen original master patterns stored inthe memory. At step 153 a, the calls corresponding to the two highestcorrelation numbers obtained up to that point are determined and saved.At step 154 a, a post-processing flag is set. At step 155 a the testpattern is compared with each of a second set of 16 or 18 masterpatterns stored in the memory. This second set of master patterns is thesame as the 16 or 18 original master patterns except that the lastsample is dropped and a zero is inserted in front of the first sample.If any of the resulting correlation numbers is higher than the twohighest numbers previously saved, the #1 and #2 answers are updated atstep 156.

Steps 155 a and 156 a are repeated at steps 157 a and 158 a, using athird set of master patterns formed by dropping the last two samplesfrom each of the 16 original master patterns and inserting two zeros infront of the first sample. At steps 159 a and 160 a the same steps arerepeated again, but using only $50 and $100 master patterns formed bydropping the last three samples from the original master patterns andadding three zeros in front of the first sample. Steps 161 a and 162 arepeat the procedure once again, using only $1, $5, $10 and $20 masterpatterns formed by dropping the 33rd sample whereby original samples34-64 become samples 33-63 and inserting a 0 as the new last sample.Finally, steps 163 a and 164 a repeat the same procedure, using masterpatterns for $10 and $50 bills printed in 1950, which differsignificantly from bills of the same denominations printed in lateryears. This routine then returns to the main program at step 165 a. Theabove multiple sets of master patterns may be pre-stored in EPROM 60.

A modified procedure involved in comparing test patterns to green-sidemaster patterns is illustrated at FIG. 18b which shows the routine asstarting at step 150 b. At step 151 b, the best and second bestcorrelation results (referred to in FIG. 18b as the “#1 and #2 answers”)are initialized to zero and, at step 152 b, the test pattern is comparedwith each of the eighteen original green-side master patterns stored inthe memory. At step 153 b, the calls corresponding to the two highestcorrelation numbers obtained up to that point are determined and saved.At step 154 b, a post-processing flag is set. At step 155 b the testpattern is compared with each of a second set of 18 green-side masterpatterns stored in the memory. This second set of master patterns is thesame as the 18 original green-side master patterns except that the lastsample is dropped and a zero is inserted in front of the first sample.If any of the resulting correlation numbers is higher than the twohighest numbers previously saved, the #1 and #2 answers are updated atstep 156 b.

Steps 155 b and 156 b are repeated at steps 157 b and 158 b, using athird set of green-side master patterns formed by dropping the last twosamples from each of the 18 original master patterns and inserting twozeros in front of the first sample. At steps 159 b and 160 b the samesteps are repeated again, but using only $50 and $100 master patterns(two patterns for the $50 and four patterns for the $100) formed bydropping the last three samples from the original master patterns andadding three zeros in front of the first sample. Steps 161 b and 162 brepeat the procedure once again, using only $1, $5, $10, $20 and $50master patterns (four patterns for the $10 and two patterns for theother denominations) formed by dropping the 33rd sample whereby originalsamples 34-64 become samples 33-63 and inserting a 0 as the new lastsample. Finally, steps 163 b and 164 b repeat the same procedure, usingmaster patterns for $10 and $50 bills printed in 1950 (two patternsscanned along a center segment for each denomination), which differsignificantly from bills of the same denominations printed in lateryears. This routine then returns to the main program at step 165 b. Theabove multiple sets of master patterns may be pre-stored in EPROM 60.

In one embodiment where conditional black-side correlation is to beperformed a modified version of the routine designated as “CORRES” isinitiated. The procedure involved in executing the modified version ofCORRES is illustrated at FIG. 19a which shows the routine as starting atstep 180. Step 181 determines whether the bill has been identified as a$2 bill, and, if the answer is negative, step 182 determines whether thebest correlation number (“call #1”) is greater than 799. If the answeris negative, the correlation number is too low to identify thedenomination of the bill with certainty, and at step 183 b a black sidecorrelation routine is called (described in more detail below inconjunction with FIGS. 19b-19 c).

An affirmative answer at step 182 advances the system to step 186, whichdetermines whether the sample data passes an ink stain test (describedbelow). If the answer is negative, a “no call” bit is set in acorrelation result flag at step 183 a. A “no call previous bill” flag isthen set at step 184, and the routine returns to the main program atstep 185. If the answer at step 186 is affirmative, the system advancesto step 187 which determines whether the best correlation number isgreater than 849. An affirmative answer at step 187 indicates that thecorrelation number is sufficiently high that the denomination of thescanned bill can be identified with certainty without any furtherchecking. Consequently, a “good call” bit is set in the correlationresult flag at step 188. A separate register associated with the bestcorrelation number (#1) may then be used to identify the denominationrepresented by the stored pattern resulting in the highest correlationnumber. The system returns to the main program at step 185.

A negative answer at step 187 indicates that the correlation number isbetween 800 and 850. It has been found that correlation numbers withinthis range are sufficient to identify all bills except the $2 bill.Accordingly, a negative response at step 187 advances the system to step189 which determines whether the difference between the two highestcorrelation numbers (“call #1” and “call #2”) is greater than 149. Ifthe answer is affirmative, the denomination identified by the highestcorrelation number is acceptable, and thus the “good call” bit is set inthe correlation result flag at step 188. If the difference between thetwo highest correlation numbers is less than 150, step 189 produces anegative response which advances the system to step 183 b where theblack side correlation routine is called.

Returning to step 181, an affirmative response at this step indicatesthat the initial call is a $2 bill. This affirmative response initiatesa series of steps 190-193 which are similar to steps 182, 186, 187 and189 described above, except that the numbers 799 and 849 used in steps182 and 187 are changed to 849 and 899, respectively, in steps 190 and192. The result is either the setting of a “no call” bit in acorrelation result flag at step 183 a, the setting of the “good call”bit in the correlation result flag at step 188, or the calling of theblack side correlation routine at step 183 b.

Turning now to FIGS. 19b and 19 c there is shown a flowchartillustrating the steps of the black side correlation routine called atstep 183 b of FIG. 19a. After the black side correlation routine isinitiated at step 600, it is determined at step 602 whether the lowerread head was the read head that scanned the black side of the testbill. If it was, the lower read head data is normalized at step 604.Otherwise, it is determined at step 606 whether the upper read head wasthe read head that scanned the black side of the test bill. If it was,the upper read head data is normalized at step 608. If it cannot bedetermined which read head scanned the black side of the bill, then thepatterns generated from both sides of the test bill were correlatedagainst the green-side master patterns (see e.g., step 110 of FIG. 12).Under such a circumstance, the no call bit in the correlation resultflag is set at step 610, the no call previous bill flag is set at step611, and the program returns to the calling point at step 612.

After the lower read head data is normalized at step 604, or the upperread head data is normalized at step 608, it is determined whether thebest green-side correlation number is greater than 700 at step 614. Anegative response at step 614 results in the no call bit in thecorrelation result flag being set at step 610, the no call previous billflag being set at step 611, and the program returning to the callingpoint at step 612. An affirmative response at step 614 results in adetermination being made as to whether the best call from the green sidecorrelation corresponds to a $20, $50, or $100 bill at step 616. Anegative response at step 616 results in the no call bit in thecorrelation result flag being set at step 610, the no call previous billflag being set at step 611, and thee program returning to the callingpoint at step 612.

If it determined at step 616 that the best call from the green sidecorrelation corresponds to a $20, $50, or $100 bill, the scanned patternfrom the black side is correlated against the black-side master patternsassociated with the specific denomination and scan direction associatedthe best call from the green side. According to one embodiment, multipleblack-side master patterns are stored for $20, $50 and $100 bills. Foreach of these denominations, three master patterns are stored for scansin the forward and three master patterns are stored for scans in thereverse direction for a total of six patterns for each denomination. Fora given scan direction, black-side master patterns are generated byscanning a corresponding denominated bill along a segment located aboutthe center of the narrow dimension of the bill, a segment slightlydisplaced (0.2 inches) to the left of center, and a segment slightlydisplaced (0.2 inches) to the right of center.

For example, at step 618, it is determined whether the best call fromthe green side is associated with a forward scan of a $20 bill and, ifit is, the normalized data from the black side of the test bill iscorrelated against the black-side master patterns associated with aforward scan of a $20 bill at step 620. Next it is determined whetherthe black-side correlation number is greater than 900 at step 622. If itis, the good call bit in the correlation result flag is set at step 648and the program returns to the calling point at step 646. If theblack-side correlation number is not greater than 900, then the no callbit in the correlation result flag is set at step 642, the no callprevious bill flag is set at step 644, and the program returns to thecalling point at step 646. If it is determined that the best call fromthe green side is not associated with a forward scan of $20 bill at step618, the program branches accordingly at steps 624-640 so that thenormalized data from the black side of the test bill is correlatedagainst the appropriate black-side master patterns.

Referring now to FIGS. 20a-22, the mechanical portions of the currencydiscrimination and counting machine include a rigid frame formed by apair of side plates 201 and 202, a pair of top plates 203 a and 203 b,and a lower front plate 204. The input receptacle for receiving a stackof bills to be processed is formed by downwardly sloping and convergingwalls 205 and 206 formed by a pair of removable covers 207 and 208 whichsnap onto the frame. The rear wall 206 supports a removable hopper 209which includes a pair of vertically disposed side walls 210 a and 210 bwhich complete the receptacle for the stack of currency bills to beprocessed.

From the input receptacle, the currency bills are moved in seriatim fromthe bottom of the stack along a curved guideway 211 which receives billsmoving downwardly and rearwardly and changes the direction of travel toa forward direction. The curvature of the guideway 211 correspondssubstantially to the curved periphery of the drive roll 223 so as toform a narrow passageway for the bills along the rear side of the driveroll. The exit end of the guideway 211 directs the bills onto a linearpath where the bills are scanned and stacked. The bills are transportedand stacked with the narrow dimension of the bills maintained parallelto the transport path and the direction of movement at all times.

Stacking of the bills is effected at the forward end of the linear path,where the bills are fed into a pair of driven stacking wheels 212 and213. These wheels project upwardly through a pair of openings in astacker plate 214 to receive the bills as they are advanced across thedownwardly sloping upper surface of the plate. The stacker wheels 212and 213 are supported for rotational movement about a shaft 215journalled on the rigid frame and driven by a motor 216. The flexibleblades of the stacker wheels deliver the bills into an output receptacle217 at the forward end of the stacker plate 214. During operation, acurrency bill which is delivered to the stacker plate 214 is picked upby the flexible blades and becomes lodged between a pair of adjacentblades which, in combination, define a curved enclosure whichdecelerates a bill entering therein and serves as a means for supportingand transferring the bill into the output receptacle 217 as the stackerwheels 212, 213 rotate. The mechanical configuration of the stackerwheels, as well as the manner in which they cooperate with the stackerplate, is conventional and, accordingly, is not described in detailherein.

Returning now to the input region of the machine as shown in FIGS.20a-22, bills that are stacked on the bottom wall 205 of the inputreceptacle are stripped, one at a time, from the bottom of the stack.The bills are stripped by a pair of stripping wheels 220 mounted on adrive shaft 221 which, in turn, is supported across the side walls 201,202. The stripping wheels 220 project through a pair of slots formed inthe cover 207. Part of the periphery of each wheel 220 is provided witha raised high-friction, serrated surface 222 which engages the bottombill of the input stack as the wheels 220 rotate, to initiate feedingmovement of the bottom bill from the stack. The serrated surfaces 222project radially beyond the rest of the wheel peripheries so that thewheels “jog” the bill stack during each revolution so as to agitate andloosen the bottom currency bill within the stack, thereby facilitatingthe stripping of the bottom bill from the stack.

The stripping wheels 220 feed each stripped bill B (FIG. 21a) onto adrive roll 223 mounted on a driven shaft 224 supported across the sidewalls 201 and 202. As can be seen most clearly in FIGS. 21a and 21 b,the drive roll 223 includes a central smooth friction surface 225 formedof a material such as rubber or hard plastic. This smooth frictionsurface 225 is sandwiched between a pair of grooved surfaces 226 and 227having serrated portions 228 and 229 formed from a high-frictionmaterial.

The serrated surfaces 228, 229 engage each bill after it is fed onto thedrive roll 223 by the stripping wheels 220, to frictionally advance thebill into the narrow arcuate passageway formed by the curved guideway211 adjacent the rear side of the drive roll 223. The rotationalmovement of the drive roll 223 and the stripping wheels 220 issynchronized so that the serrated surfaces on the drive roll and thestripping wheels maintain a constant relationship to each other.Moreover, the drive roll 223 is dimensioned so that the circumference ofthe outermost portions of the grooved surfaces is greater than the widthW of a bill, so that the bills advanced by the drive roll 223 are spacedapart from each other, for the reasons discussed above. That is, eachbill fed to the drive roll 223 is advanced by that roll only when theserrated surfaces 228, 229 come into engagement with the bill, so thatthe circumference of the drive roll 223 determines the spacing betweenthe leading edges of successive bills.

To avoid the simultaneous removal of multiple bills from the stack inthe input receptacle, particularly when small stacks of bills are loadedinto the machine, the stripping wheels 220 are always stopped with theraised, serrated portions 222 positioned below the bottom wall 205 ofthe input receptacle. This is accomplished by continuously monitoringthe angular position of the serrated portions of the stripping wheels220 via the encoder 32, and then controlling the stopping time of thedrive motor so that the motor always stops the stripping wheels in aposition where the serrated portions 222 are located beneath the bottomwall 205 of the input receptacle. Thus, each time a new stack of billsis loaded into the machine, those bills will rest on the smooth portionsof the stripping wheels. This has been found to significantly reduce thesimultaneous feeding of double or triple bills, particularly when smallstacks of bills are involved.

In order to ensure firm engagement between the drive roll 223 and thecurrency bill being fed, an idler roll 230 urges each incoming billagainst the smooth central surface 225 of the drive roll 223. The idlerroll 230 is journalled on a pair of arms 231 which are pivotally mountedon a support shaft 232. Also mounted on the shaft 232, on opposite sidesof the idler roll 230, are a pair of grooved guide wheels 233 and 234.The grooves in these two wheels 233, 234 are registered with the centralribs in the two grooved surfaces 226, 227 of the drive roll 223. Thewheels 233, 234 are locked to the shaft 232, which in turn is lockedagainst movement in the direction of the bill movement (clockwise asview in FIG. 20a) by a one-way spring clutch 235. Each time a bill isfed into the nip between the guide wheels 233, 234 and the drive roll223, the clutch 235 is energized to turn the shaft 232 just a fewdegrees in a direction opposite the direction of bill movement. Theserepeated incremental movements distribute the wear uniformly around thecircumferences of the guide wheels 233, 234. Although the idler roll 230and the guide wheels 233, 234 are mounted behind the guideway 211, theguideway is apertured to allow the roll 230 and the wheels 233, 234 toengage the bills on the front side of the guideway.

Beneath the idler roll 230, a spring-loaded pressure roll 236 (FIGS. 20aand 21 b) presses the bills into firm engagement with the smoothfriction surface 225 of the drive roll as the bills curve downwardlyalong the guideway 211. This pressure roll 236 is journalled on a pairof arms 237 pivoted on a stationary shaft 238. A spring 239 attached tothe lower ends of the arms 237 urges the roll 236 against the drive roll223, through an aperture in the curved guideway 211.

At the lower end of the curved guideway 211, the bill being transportedby the drive roll 223 engages a flat guide plate 240 which carries alower scan head 18. Currency bills are positively driven along the flatplate 240 by means of a transport roll arrangement which includes thedrive roll 223 at one end of the plate and a smaller driven roll 241 atthe other end of the plate. Both the driver roll 223 and the smallerroll 241 include pairs of smooth raised cylindrical surfaces 242 and 243which hold the bill flat against the plate 240. A pair of O rings 244and 245 fit into grooves formed in both the roll 241 and the roll 223 toengage the bill continuously between the two rolls 223 and 241 totransport the bill while helping to hold the bill flat against the guideplate 240.

The flat guide plate 240 is provided with openings through which theraised surfaces 242 and 243 of both the drive roll 223 and the smallerdriven roll 241 are subjected to counter-rotating contact withcorresponding pairs of passive transport rolls 250 and 251 havinghigh-friction rubber surfaces. The passive rolls 250, 251 are mounted onthe underside of the flat plate 240 in such a manner as to befreewheeling about their axes 254 and 255 and biased intocounter-rotating contact with the corresponding upper rolls 223 and 241.The passive rolls 250 and 251 are biased into contact with the drivenrolls 223 and 241 by means of a pair of H-shaped leaf springs 252 and253 (see FIGS. 23 and 24). Each of the four rolls 250, 251 is cradledbetween a pair of parallel arms of one of the H-shaped leaf springs 252and 253. The central portion of each leaf spring is fastened to theplate 240, which is fastened rigidly to the machine frame, so that therelatively stiff arms of the H-shaped springs exert a constant biasingpressure against the rolls and push them against the upper rolls 223 and241.

The points of contact between the driven and passive transport rolls arepreferably coplanar with the flat upper surface of the plate 240 so thatcurrency bills can be positively driven along the top surface of theplate in a flat manner. The distance between the axes of the two driventransport rolls, and the corresponding counter-rotating passive rolls,is selected to be just short of the length of the narrow dimension ofthe currency bills. Accordingly, the bills are firmly gripped underuniform pressure between the upper and lower transport rolls within thescanhead area, thereby minimizing the possibility of bill skew andenhancing the reliability of the overall scanning and recognitionprocess.

The positive guiding arrangement described above is advantageous in thatuniform guiding pressure is maintained on the bills as they aretransported through the optical scanhead area, and twisting or skewingof the bills is substantially reduced. This positive action issupplemented by the use of the H-springs 252, 253 for uniformly biasingthe passive rollers into contact with the active rollers so that billtwisting or skew resulting from differential pressure applied to thebills along the transport path is avoided. The O-rings 244, 245 functionas simple, yet extremely effective means for ensuring that the centralportions of the bills are held flat.

The location of a magnetic head 256 and a magnetic head adjustment screw257 are illustrated in FIG. 23. The adjustment screw 257 adjusts theproximity of the magnetic head 256 relative to a passing bill andthereby adjusts the strength of the magnetic field in the vicinity ofthe bill.

FIG. 22 shows the mechanical arrangement for driving the various meansfor transporting currency bills through the machine. A motor 260 drivesa shaft 261 carrying a pair of pulleys 262 and 263. The pulley 262drives the roll 241 through a belt 264 and pulley 265, and the pulley263 drives the roll 223 through a belt 266 and pulley 267. Both pulleys265 and 267 are larger than pulleys 262 and 263 in order to achieve thedesired speed reduction from the typically high speed at which the motor260 operates.

The shaft 221 of the stripping wheels 220 is driven by means of a pulley268 provided thereon and linked to a corresponding pulley 269 on theshaft 224 through a belt 270. The pulleys 268 and 269 are of the samediameter so that the shafts 221 and 224 rotate in unison.

As shown in FIG. 20b, the optical encoder 32 is mounted on the shaft ofthe roller 241 for precisely tracking the position of each bill as it istransported through the machine, as discussed in detail above inconnection with the optical sensing and correlation technique.

The upper and lower scanhead assemblies are shown most clearly in FIGS.25-28. It can be seen that the housing for each scanhead is formed as anintegral part of a unitary molded plastic support member 280 or 281 thatalso forms the housings for the light sources and photodetectors of thephotosensors PS1 and PS2. The lower member 281 also forms the flat guideplate 240 that receives the bills from the drive roll 223 and supportsthe bills as they are driven past the scanheads 18 a and 18 b.

The two support members 280 and 281 are mounted facing each other sothat the lenses 282 and 283 of the two scanheads 18 a, 18 b define anarrow gap through which each bill is transported. Similar, but slightlylarger, gaps are formed by the opposed lenses of the light sources andphotodetectors of the photosensors PS1 and PS2. The upper support member280 includes a tapered entry guide 280 a which guides an incoming billinto the gaps between the various pairs of opposed lenses.

The lower support member 281 is attached rigidly to the machine frame.The upper support member 280, however, is mounted for limited verticalmovement when it is lifted manually by a handle 284, to facilitate theclearing of any paper jams that occur beneath the member 280. To allowfor such vertical movement, the member 280 is slidably mounted on a pairof posts 285 and 286 on the machine frame, with a pair of springs 287and 288 biasing the member 280 to its lowermost position.

Each of the two optical scanheads 18 a and 18 b housed in the supportmembers 280, 281 includes a pair of light sources acting in combinationto uniformly illuminate light strips of the desired dimension onopposite sides of a bill as it is transported across the plate 240.Thus, the upper scanhead 18 a includes a pair of LEDs 22 a, directinglight downwardly through an optical mask on top of the lens 282 onto abill traversing the flat guide plate 240 beneath the scanhead. The LEDs22 a are angularly disposed relative to the vertical axis of thescanhead so that their respective light beams combine to illuminate thedesired light strip defined by an aperture in the mask. The scanhead 18a also includes a photodetector 26 a mounted directly over the center ofthe illuminated strip for sensing the light reflected off the strip. Thephotodetector 26 a is linked to the CPU 30 through the ADC 28 forprocessing the sensed data as described above.

When the photodetector 26 a is positioned on an axis passing through thecenter of the illuminated strip, the illumination by the LED's as afunction of the distance from the central point “0” along the X axis,should optimally approximate a step function as illustrated by the curveA in FIG. 29. With the use of a single light source angularly displacedrelative to a vertical axis through the center of the illuminated strip,the variation in illumination by an LED typically approximates aGaussian function, as illustrated by the curve B in FIG. 29.

The two LEDs 22 a are angularly disposed relative to the vertical axisby angles α and β, respectively. The angles α and β are selected to besuch that the resultant strip illumination by the LED's is as close aspossible to the optimum distribution curve A in FIG. 29. The LEDillumination distribution realized by this arrangement is illustrated bythe curve designated as “C” in FIG. 29 which effectively merges theindividual Gaussian distributions of each light source to yield acomposite distribution which sufficiently approximates the optimum curveA.

In the particular embodiment of the scanheads 18 a and 18 b illustratedin the drawings, each scanhead includes two pairs of LEDs and twophotodetectors for illuminating, and detecting light reflected from,strips of two different sizes. Thus, each mask also includes two slitswhich are formed to allow light from the LEDs to pass through andilluminate light strips of the desired dimensions. More specifically,one slit illuminates a relatively wide strip used for obtaining thereflectance samples which correspond to the characteristic pattern for atest bill. In one embodiment, the wide slit has a length of about 0.500″and a width of about 0.050″. The second slit forms a relatively narrowilluminated strip used for detecting the thin borderline surrounding theprinted indicia on currency bills, as described above in detail. In oneembodiment, the narrow slit 283 has a length of about 0.300″ and a widthof about 0.010″.

In order to prevent dust from fouling the operation of the scanheads,each scanhead includes three resilient seals or gaskets 290, 291, and292. The two side seals 290 and 291 seal the outer ends of the LEDs 22,while the center seal 292 seals the outer end of the photodetector 26.Thus, dust cannot collect on either the light sources or thephotodetectors, and cannot accumulate and block the slits through whichlight is transmitted from the sources to the bill, and from the bill tothe photodetectors.

Doubling or overlapping of bills in the illustrative transport system isdetected by two photosensors PS1 and PS2 which are located on a commontransverse axis that is perpendicular to the direction of bill flow (seee.g., FIGS. 30a and 30 b). The photosensors PS1 and PS2 includephotodetectors 293 and 294 mounted within the lower support member 281in immediate opposition to corresponding light sources 295 and 296mounted in the upper support member 280. The photodetectors 293, 294detect beams of light directed downwardly onto the bill transport pathfrom the light sources 295, 296 and generate analog outputs whichcorrespond to the sensed light passing through the bill. Each suchoutput is converted into a digital signal by a conventional ADCconvertor unit (not shown) whose output is fed as a digital input to andprocessed by the system CPU.

The presence of a bill adjacent the photosensors PS1 and PS2 causes achange in the intensity of the detected light, and the correspondingchanges in the analog outputs of the photodetectors 293 and 294 serve asa convenient means for density-based measurements for detecting thepresence of “doubles” (two or more overlaid or overlapped bills) duringthe currency scanning process. For instance, the photosensors may beused to collect a predefined number of density measurements on a testbill, and the average density value for a bill may be compared topredetermined density thresholds (based, for instance, on standardizeddensity readings for master bills) to determine the presence of overlaidbills or doubles.

In order to prevent the accumulation of dirt on the light sources 295and 296 and/or the photodetectors 293, 294 of the photosensors PS1 andPS2, both the light sources and the photodetectors are enclosed bylenses mounted so close to the bill path that they are continually wipedby the bills. This provides a self-cleaning action which reducesmaintenance problems and improves the reliability of the outputs fromthe photosensors over long periods of operation.

The CPU 30, under control of software stored in the EPROM 34, monitorsand controls the speed at which the bill transport mechanism 16transports bills from the bill separating station 14 to the billstacking unit. Flowcharts of the speed control routines stored in theEPROM 34 are depicted in FIGS. 31-35. To execute more than the firststep in any given routine, the currency discriminating system 10 must beoperating in a mode requiring the execution of the routine.

Referring first to FIG. 31, when a user places a stack of bills in thebill accepting station 12 for counting, the transport speed of the billtransport mechanism 16 must accelerate or “ramp up” from zero to topspeed. Therefore, in response to receiving the stack of bills in thebill accepting station 12, the CPU 30 sets a ramp-up bit in a motor flagstored in the memory unit 38. Setting the ramp-up bit causes the CPU 30to proceed beyond step 300 b of the ramp-up routine. If the ramp-up bitis set, the CPU 30 utilizes a ramp-up counter and a fixed parameter“ramp-up step” to incrementally increase the transport speed of the billtransport mechanism 16 until the bill transport mechanism 16 reaches itstop speed. The “ramp-up step” is equal to the incremental increase inthe transport speed of the bill transport mechanism 16, and the ramp-upcounter determines the amount of time between incremental increases inthe bill transport speed. The greater the value of the “ramp-up step”,the greater the increase in the transport speed of the bill transportmechanism 16 at each increment. The greater the maximum value of theramp-up counter, the greater the amount of time between increments.Thus, the greater the value of the “ramp-up step” and the lesser themaximum value of the ramp-up counter, the lesser the time it takes thebill transport mechanism 16 to reach its top speed.

The ramp-up routine in FIG. 31 employs a variable parameter “new speed”,a fixed parameter “full speed”, and the variable parameter “transportspeed”. The “full speed” represents the top speed of the bill transportmechanism 16, while the “new speed” and “transport speed” represent thedesired current speed of the bill transport mechanism 16. To account foroperating offsets of the bill transport mechanism 16, the “transportspeed” of the bill transport mechanism 16 actually differs from the “newspeed” by a “speed offset value”. Outputting the “transport speed” tothe bill transport mechanism 16 causes the bill transport mechanism 16to operate at the transport speed.

To incrementally increase the speed of the bill transport mechanism 16,the CPU 30 first decrements the ramp-up counter from its maximum value(step 301). If the maximum value of the ramp-up counter is greater thanone at step 302, the CPU 30 exits the speed control software in FIGS.31-35 and repeats steps 300 b, 301, and 302 during subsequent iterationsof the ramp-up routine until the ramp-up counter is equal to zero. Whenthe ramp-up counter is equal to zero, the CPU 30 resets the ramp-upcounter to its maximum value (step 303). Next, the CPU 30 increases the“new speed” by the “ramp-up step” (step 304). If the “new speed” is notyet equal to the “full speed” at step 305, the “transport speed” is setequal to the “new speed” plus the “speed offset value” (step 306). The“transport speed” is output to the bill transport mechanism 16 at step307 of the routine in FIG. 31 to change the speed of the bill transportmechanism 16 to the “transport speed”. During subsequent iterations ofthe ramp-up routine, the CPU 30 repeats steps 300 b-306 until the “newspeed” is greater than or equal to the “full speed”.

Once the “new speed” is greater than or equal to the “full speed” atstep 305, the ramp-up bit in the motor flag is cleared (step 308), apause-after-ramp bit in the motor flag is set (step 309), apause-after-ramp counter is set to its maximum value (step 310), and theparameter “new speed” is set equal to the “full speed” (step 311).Finally, the “transport speed” is set equal to the “new speed” plus the“speed offset value” (step 306). Since the “new speed” is equal to the“full speed”, outputting the “transport speed” to the bill transportmechanism 16 causes the bill transport mechanism 16 to operate at itstop speed. The ramp-up routine in FIG. 31 smoothly increases the speedof the bill transport mechanism without causing jerking or motor spikes.Motor spikes could cause false triggering of the optical scanhead 18such that the scanhead 18 scans non-existent bills.

During normal counting, the bill transport mechanism 16 transports billsfrom the bill separating station 14 to the bill stacking unit at its topspeed. In response to the optical scanhead 18 detecting a stranger,suspect or no call bill, however, the CPU 30 sets a ramp-to-slow-speedbit in the motor flag. Setting the ramp-to-slow-speed bit causes the CPU30 to proceed beyond step 312 of the ramp-to-slow-speed routine in FIG.32 on the next iteration of the software in FIGS. 31-35. Using theramp-to-slow-speed routine in FIG. 32, the CPU 30 causes the billtransport mechanism 16 to controllably decelerate or “ramp down” fromits top speed to a slow speed. As the ramp-to-slow speed routine in FIG.32 is similar to the ramp-up routine in FIG. 31, it is not described indetail herein.

It suffices to state that if the ramp-to-slow-speed bit is set in themotor flag, the CPU 30 decrements a ramp-down counter (step 313) anddetermines whether or not the ramp-down counter is equal to zero (step314). If the ramp-down counter is not equal to zero, the CPU 30 exitsthe speed control software in FIGS. 31-35 and repeats steps 312, 313,and 314 of the ramp-to-slow-speed routine in FIG. 32 during subsequentiterations of the speed control software until the ramp-down counter isequal to zero. Once the ramp-down counter is equal to zero, the CPU 30resets the ramp-down counter to its maximum value (step 315) andsubtracts a “ramp-down step” from the variable parameter “new speed”(step 316). The “new speed” is equal to the fixed parameter “full speed”prior to initiating the ramp-to-slow-speed routine in FIG. 32.

After subtracting the “ramp-down step” from the “new speed”, the “newspeed ” is compared to a fixed parameter “slow speed” (step 317). If the“new speed” is greater than the “slow speed”, the “transport speed” isset equal to the “new speed” plus the “speed offset value” (step 318)and this “transport speed” is output to the bill transport mechanism 16(step 307 of FIG. 31). During subsequent iterations of theramp-to-slow-speed routine, the CPU 30 continues to decrement the “newspeed” by the “ramp-down step” until the “new speed” is less than orequal to the “slow speed”. Once the “new speed” is less than or equal tothe “slow speed” at step 317, the CPU 30 clears the ramp-to-slow-speedbit in the motor flag (step 319), sets the pause-after-ramp bit in themotor flag (step 320), sets the pause-after-ramp counter (step 321), andsets the “new speed” equal to the “slow speed” (step 322). Finally, the“transport speed” is set equal to the “new speed” plus the “speed offsetvalue” (step 318). Since the “new speed” is equal to the “slow speed”,outputting the “transport speed” to the bill transport mechanism 16causes the bill transport mechanism 16 to operate at its slow speed. Theramp-to-slow-speed routine in FIG. 32 smoothly decreases the speed ofthe bill transport mechanism 16 without causing jerking or motor spikes.

FIG. 33 depicts a ramp-to-zero-speed routine in which the CPU 30 rampsdown the transport speed of the bill transport mechanism 16 to zeroeither from its top speed or its slow speed. In response to completionof counting of a stack of bills, the CPU 30 enters this routine to rampdown the transport speed of the bill transport mechanism 16 from its topspeed to zero. Similarly, in response to the optical scanhead 18detecting a stranger, suspect, or no call bill and theramp-to-slow-speed routine in FIG. 32 causing the transport speed to beequal to a slow speed, the CPU 30 enters the ramp-to-zero-speed routineto ramp down the transport speed from the slow speed to zero.

With the ramp-to-zero-speed bit set at step 323, the CPU 30 determineswhether or not an initial-braking bit is set in the motor flag (step324). Prior to ramping down the transport speed of the bill transportmechanism 16, the initial-braking bit is clear. Therefore, flow proceedsto the left branch of the ramp-to-zero-speed routine in FIG. 33. In thisleft branch, the CPU 30 sets the initial-braking bit in the motor flag(step 325), resets the ramp-down counter to its maximum value (step326), and subtracts an “initial-braking step” from the variableparameter “new speed” (step 327). Next, the CPU 30 determines whether ornot the “new speed” is greater than zero (step 328). If the “new speed”is greater than zero at step 328, the variable parameter “transportspeed” is set equal to the “new speed” plus the “speed offset value”(step 329) and this “transport speed” is output to the bill transportmechanism 16 at step 307 in FIG. 31.

During the next iteration of the ramp-to-zero-speed routine in FIG. 33,the CPU 30 enters the right branch of the routine at step 324 becausethe initial-braking bit was set during the previous iteration of theramp-to-zero-speed routine. With the initial-braking bit set, the CPU 30decrements the ramp-down counter from its maximum value (step 330) anddetermines whether or not the ramp-down counter is equal to zero (step331). If the ramp-down counter is not equal to zero, the CPU 30immediately exits the speed control software in FIGS. 31-35 and repeatssteps 323, 324, 330, and 331 of the ramp-to-slow-speed routine duringsubsequent iterations of the speed control software until the ramp-downcounter is equal to zero. Once the ramp-down counter is equal to zero,the CPU 30 resets the ramp-down counter to its maximum value (step 332)and subtracts a “ramp-down step” from the variable parameter “new speed”(step 333). This “ramp-down step” is smaller than the “initial-brakingstep” so that the “initial-braking step” causes a larger decrementalchange in the transport speed of the bill transport mechanism 16 thanthat caused by the “ramp-down step”.

Next, the CPU 30 determines whether or not the “new speed” is greaterthan zero (step 328). If the “new speed” is greater than zero, the“transport speed” is set equal to the “new speed” plus the “speed offsetvalue” (step 329) and this “transport speed” is outputted to the billtransport mechanism 16 (step 307 in FIG. 31). During subsequentiterations of the speed control software, the CPU 30 continues todecrement the “new speed” by the “ramp-down step” at step 333 until the“new speed” is less than or equal to zero at step 328. Once the “newspeed” is less than or equal to the zero at step 328, the CPU 30 clearsthe ramp-to-zero-speed bit and the initial-braking bit in the motor flag(step 334), sets a motor-at-rest bit in the motor flag (step 335), andsets the “new speed” equal to zero (step 336). Finally, the “transportspeed” is set equal to the “new speed” plus the “speed offset value”(step 329). Since the “new speed” is equal to zero, outputting the“transport speed” to the bill transport mechanism 16 at step 307 in FIG.31 halts the bill transport mechanism 16.

Using the feedback loop routine in FIG. 35, the CPU 30 monitors andstabilizes the transport speed of the bill transport mechanism 16 whenthe bill transport mechanism 16 is operating at its top speed or at slowspeed. To measure the transport speed of the bill transport mechanism16, the CPU 30 monitors the optical encoder 32. While monitoring theoptical encoder 32, it is important to synchronize the feedback looproutine with any transport speed changes of the bill transport mechanism16. To account for the time lag between execution of the ramp-up orramp-to-slow-speed routines in FIGS. 31-32 and the actual change in thetransport speed of the bill transport mechanism 16, the CPU 30 enters apause-after-ramp routine in FIG. 34 prior to entering the feedback looproutine in FIG. 35 if the bill transport mechanism 16 completed rampingup to its top speed or ramping down to slow speed during the previousiteration of the speed control software in FIGS. 31-35.

The pause-after-ramp routine in FIG. 34 allows the bill transportmechanism 16 to “catch up” to the CPU 30 so that the CPU 30 does notenter the feedback loop routine in FIG. 35 prior to the bill transportmechanism 16 changing speeds. As stated previously, the CPU 30 sets apause-after-ramp bit during step 309 of the ramp-up routine in FIG. 31or step 320 of the ramp-to-slow-speed routine in FIG. 32. With thepause-after-ramp bit set, flow proceeds from step 337 of thepause-after-ramp routine to step 338, where the CPU 30 decrements apause-after-ramp counter from its maximum value. If the pause-after-rampcounter is not equal to zero at step 339, the CPU 30 exits thepause-after-ramp routine in FIG. 34 and repeats steps 337, 338, and 339of the pause-after-ramp routine during subsequent iterations of thespeed control software until the pause-after-ramp counter is equal tozero. Once the pause-after-ramp counter decrements to zero, the CPU 30clears the pause-after-ramp bit in the motor flag (step 340) and setsthe feedback loop counter to its maximum value (step 341). The maximumvalue of the pause-after-ramp counter is selected to delay the CPU 30 byan amount of time sufficient to permit the bill transport mechanism 16to adjust to a new transport speed prior to the CPU 30 monitoring thenew transport speed with the feedback loop routine in FIG. 35.

Referring now to the feedback loop routine in FIG. 35, if themotor-at-rest bit in the motor flag is not set at step 342, the CPU 30decrements a feedback loop counter from its maximum value (step 343). Ifthe feedback loop counter is not equal to zero at step 344, the CPU 30immediately exits the feedback loop routine in FIG. 35 and repeats steps342, 343, and 344 of the feedback loop routine during subsequentiterations of the speed control software in FIGS. 31-36 until thefeedback loop counter is equal to zero. Once the feedback loop counteris decremented to zero, the CPU 30 resets the feedback loop counter toits maximum value (step 345), stores the present count of the opticalencoder 32 (step 346), and calculates a variable parameter “actualdifference” between the present count and a previous count of theoptical encoder 32 (step 347). The “actual difference” between thepresent and previous encoder counts represents the transport speed ofthe bill transport mechanism 16. The larger the “actual difference”between the present and previous encoder counts, the greater thetransport speed of the bill transport mechanism. The CPU 30 subtractsthe “actual difference” from a fixed parameter “requested difference” toobtain a variable parameter “speed difference” (step 348).

If the “speed difference” is greater than zero at step 349, the billtransport speed of the bill transport mechanism 16 is too slow. Tocounteract slower than ideal bill transport speeds, the CPU 30multiplies the “speed difference” by a “gain constant” (step 354) andsets the variable parameter “transport speed” equal to the multiplieddifference from step 354 plus the “speed offset value” plus a fixedparameter “target speed” (step 355). The “target speed” is a value that,when added to the “speed offset value”, produces the ideal transportspeed. The calculated “transport speed” is greater than this idealtransport speed by the amount of the multiplied difference. If thecalculated “transport speed” is nonetheless less than or equal to afixed parameter “maximum allowable speed” at step 356, the calculated“transport speed” is output to the bill transport mechanism 16 at step307 so that the bill transport mechanism 16 operates at the calculated“transport speed”. If, however, the calculated “transport speed” isgreater than the “maximum allowable speed” at step 356, the parameter“transport speed” is set equal to the “maximum allowable speed” (step357) and is output to the bill transport mechanism 16 (step 307).

If the “speed difference” is less than or equal to zero at step 349, thebill transport speed of the bill transport mechanism 16 is too fast oris ideal. To counteract faster than ideal bill transport speeds, the CPU30 multiplies the “speed difference” by a “gain constant” (step 350) andsets the variable parameter “transport speed” equal to the multiplieddifference from step 350 plus the “speed offset value” plus a fixedparameter “target speed” (step 351). The calculated “transport speed” isless than this ideal transport speed by the amount of the multiplieddifference. If the calculated “transport speed” is nonetheless greaterthan or equal to a fixed parameter “minimum allowable speed” at step352, the calculated “transport speed” is output to the bill transportmechanism 16 at step 307 so that the bill transport mechanism 16operates at the calculated “transport speed”. If, however, thecalculated “transport speed” is less than the “minimum allowable speed”at step 352, the parameter “transport speed” is set equal to the“minimum allowable speed” (step 353) and is output to the bill transportmechanism 16 (step 307).

It should be apparent that the smaller the value of the “gain constant”,the smaller the variations of the bill transport speed betweensuccessive iterations of the feedback control routine in FIG. 35 and,accordingly, the less quickly the bill transport speed is adjustedtoward the ideal transport speed. Despite these slower adjustments inthe bill transport speed, it is generally preferred to use a relativelysmall “gain constant” to prevent abrupt fluctuations in the billtransport speed and to prevent overshooting the ideal bill transportspeed.

A routine for using the outputs of the two photosensors PS1 and PS2 todetect any doubling or overlapping of bills is illustrated in FIG. 36 bysensing the optical density of each bill as it is scanned. This routinestarts at step 401 and retrieves the denomination determined for thepreviously scanned bill at step 402. This previously determineddenomination is used for detecting doubles in the event that the newlyscanned bill is a “no call”, as described below. Step 403 determineswhether the current bill is a “no call,” and if the answer is negative,the denomination determined for the new bill is retrieved at step 404.

If the answer at step 403 is affirmative, the system jumps to step 405,so that the previous denomination retrieved at step 402 is used insubsequent steps. To permit variations in the sensitivity of the densitymeasurement, a “density setting” is retrieved from memory at step 405.The operator makes this choice manually, according to whether the billsbeing scanned are new bills, requiring a high degree of sensitivity, orused bills, requiring a lower level of sensitivity. If the “densitysetting” has been turned off, this condition is sensed at step 406, andthe system returns to the main program at step 413. If the “densitysetting” is not turned off, a denominational density comparison value isretrieved from memory at step 407.

The memory according to one embodiment contains five different densityvalues (for five different density settings, i.e., degrees ofsensitivity) for each denomination. Thus, for a currency set containingseven different denominations, the memory contains 35 different values.The denomination retrieved at step 404 (or step 402 in the event of a“no call”), and the density setting retrieved st step 405, determinewhich of the 35 stored values is retrieved at stop 407 for use in thecomparison steps described below.

At step 408, the density comparison value retrieved at step 407 iscompared to the average density represented by the output of thephotosensor PS1. The result of this comparison is evaluated at step 409to determine whether the output of sensor S1 identifies a doubling ofbills for the particular denomination of bill determined at step 402 or404. If the answer is negative, the system returns to the main programat step 413. If the answer is affirmative, step 410 then compares theretrieved density comparison value to the average density represented bythe output of the second sensor PS2. The result of this comparison isevaluated at step 411 to determine whether the output of the photosensorPS2 identifies a doubling of bills. Affirmative answers at both step 409and step 411 result in the setting of a “doubles error” flag at step412, and the system then returns to the main program at step 413. The“doubles error” flag can, of course, be used to stop the bill transportmotor.

FIG. 37 illustrates a routine that enables the system to detect billswhich have been badly defaced by dark marks such as ink blotches,felt-tip pen marks and the like. Such severe defacing of a bill canresult in such distorted scan data that the data can be interpreted toindicate the wrong denomination for the bill. Consequently, it isdesirable to detect such severely defaced bills and then stop the billtransport mechanism so that the bill in question can be examined by theoperator.

The routine of FIG. 37 retrieves each successive data sample at step 450b and then advances to step 451 to determine whether that sample is toodark. As described above, the output voltage from the photodetector 26decreases as the darkness of the scanned area increases. Thus, the lowerthe output voltage from the photodetector, the darker the scanned area.For the evaluation carried out at step 451, a preselected thresholdlevel for the photodetector output voltage, such as a threshold level ofabout 1 volt, is used to designate a sample that is “too dark.”

An affirmative answer at step 451 advances the system to step 452 wherea “bad sample” count is incremented by one. A single sample that is toodark is not enough to designate the bill as seriously defaced. Thus, the“bad sample” count is used to determine when a preselected number ofconsecutive samples, e.g., ten consecutive samples, are determined to betoo dark. From step 452, the system advances to step 453 to determinewhether ten consecutive bad samples have been received. If the answer isaffirmative, the system advances to step 454 where an error flag is set.This represents a “no call” condition, which causes the bill transportsystem to be stopped in the same manner discussed above.

When a negative response is obtained at step 451, the system advances tostep 455 where the “bad sample” count is reset to zero, so that thiscount always represents the number of consecutive bad samples received.From step 455 the system advances to step 456 which determines when allthe samples for a given bill have been checked. As long as step 456yields a negative answer, the system continues to retrieve successivesamples at step 450 b. When an affirmative answer is produced at step456, the system returns to the main program at step 457.

A routine for automatically monitoring and making any necessarycorrections in various line voltages is illustrated in FIG. 38. Thisroutine is useful in automatically compensating for voltage drifts dueto temperature changes, aging of components and the like. The routinestarts at step 550 and reads the output of a line sensor which ismonitoring a selected voltage at step 550 b. Step 551 determines whetherthe reading is below 0.60, and if the answer is affirmative, step 552determines whether the reading is above 0.40. If step 552 also producesan affirmative response, the voltage is within the required range andthus the system returns to the main program step 553. If step 551produces a negative response, an incremental correction is made at step554 to reduce the voltage in an attempt to return it to the desiredrange. Similarly, if a negative response is obtained at step 552, anincremental correction is made at step 555 to increase the voltagetoward the desired range.

Now that a currency scanner has been described in connection withscanning U.S. currency, an additional currency discrimination system ofthe present invention will be described.

First of all, because currencies come in a variety of sizes, sensors areadded to determine the size of a bill to be scanned. These sensors areplaced upstream of the scanheads to be described below. One embodimentof size determining sensors is illustrated in FIG. 39. Twoleading/trailing edge sensors 1062 detect the leading and trailing edgesof a bill 1064 as it passing along the transport path. These sensors inconjunction with the encoder 32 (FIGS. 2a-2 b) may be used to determinethe dimension of the bill along a direction parallel to the scandirection which in FIG. 39 is the narrow dimension (or width) of thebill 1064. Additionally, two side edge sensors 1066 are used to detectthe dimension of a bill 1064 transverse to the scan direction which inFIG. 39 is the wide dimension (or length) of the bill 1064. While thesensors 1062 and 1066 of FIG. 39 are optical sensors, other means ofdetermining the size of a bill may be employed.

Once the size of a bill is determined, the potential identity of thebill is limited to those bills having the same size. Accordingly, thearea to be scanned can be tailored to the area or areas best suited foridentifying the denomination and country of origin of a bill having themeasured dimensions.

Secondly, while the printed indicia on U.S. currency is enclosed withina thin borderline, the sensing of which may serve as a trigger to beginscanning using a wider slit, most currencies of other currency systemssuch as those from other countries do not have such a borderline. Thusthe system described above may be modified to begin scanning relative tothe edge of a bill for currencies lacking such a borderline. Referringto FIG. 40, two leading edge detectors 1068 are shown. The detection ofthe leading edge 1069 of a bill 1070 by leading edge sensors 1068triggers scanning in an area a given distance away from the leading edgeof the bill 1070, e.g., D₁ or D₂, which may vary depending upon thepreliminary indication of the identity of a bill based on the dimensionsof a bill. Alternatively, the leading edge 1069 of a bill may bedetected by one or more of the scanheads (to be described below) in asimilar manner as that described with respect to FIGS. 7a and 7 b.Alternatively, the beginning of scanning may be triggered by positionalinformation provided by the encoder 32 of FIGS. 2a-2 b, for example, inconjunction with the signals provided by sensors 1062 of FIG. 39, thuseliminating the need for leading edge sensors 1068.

However, when the initiation of scanning is triggered by the detectionof the leading edge of a bill, the chance that a scanned pattern will beoffset relative to a corresponding master pattern increases. Offsets canresult from the existence of manufacturing tolerances which permit thelocation of printed indicia of a document to vary relative to the edgesof the document. For example, the printed indicia on U.S. bills may varyrelative to the leading edge of a bill by as much as 50 mils which is0.05 inches (1.27 mm). Thus when scanning is triggered relative to theedge of a bill (rather than the detection of a certain part of theprinted indicia itself, such as the printed borderline of U.S. bills), ascanned pattern can be offset from a corresponding master pattern by oneor more samples. Such offsets can lead to erroneous rejections ofgenuine bills due to poor correlation between scanned and masterpatterns. To compensate, overall scanned patterns and master patternscan be shifted relative to each other as illustrated in FIGS. 41a and 41b. More particularly, FIG. 41a illustrates a scanned pattern which isoffset from a corresponding master pattern. FIG. 41b illustrates thesame patterns after the scanned pattern is shifted relative to themaster pattern, thereby increasing the correlation between the twopatterns. Alternatively, instead of shifting either scanned patterns ormaster patterns, master patterns may be stored in memory correspondingto different offset amounts.

Thirdly, while it has been determined that the scanning of the centralarea on the green side of a U.S. bill (see segment S of FIG. 4) providessufficiently distinct patterns to enable discrimination among theplurality of U.S. denominations, the central area may not be suitablefor bills originating in other countries. For example, for billsoriginating from Country 1, it may be determined that segment S₁ (FIG.40) provides a more preferable area to be scanned, while segment S₂(FIG. 40) is more preferable for bills originating from Country 2.Alternatively, in order to sufficiently discriminate among a given setof bills, it may be necessary to scan bills which are potentially fromsuch set along more than one segment, e.g., scanning a single bill alongboth S₁ and S₂. To accommodate scanning in areas other than the centralportion of a bill, multiple scanheads may be positioned next to eachother. One embodiment of such a multiple scanhead system is depicted inFIG. 42. Multiple scanheads 1072 a-c and 1072 d-f are positioned next toeach other along a direction lateral to the direction of bill movement.Such a system permits a bill 1074 to be scanned along differentsegments. Multiple scanheads 1072 a-f are arranged on each side of thetransport path, thus permitting both sides of a bill 1074 to be scanned.

Two-sided scanning may be used to permit bills to be fed into a currencydiscrimination system according to the present invention with eitherside face up. An example of a two-sided scanhead arrangement isdescribed above in connection with FIGS. 2a, 6 c, and 6 d. Masterpatterns generated by scanning genuine bills may be stored for segmentson one or both sides. In the case where master patterns are stored fromthe scanning of only one side of a genuine bill, the patterns retrievedby scanning both sides of a bill under test may be compared to a masterset of single-sided master patterns. In such a case, a pattern retrievedfrom one side of a bill under test should match one of the stored masterpatterns, while a pattern retrieved from the other side of the billunder test should not match one of the master patterns. Alternatively,master patterns may be stored for both sides of genuine bills. In such atwo-sided system, a pattern retrieved by scanning one side of a billunder test should match with one of the master patterns of one side(Match 1) and a pattern retrieved from scanning the opposite side of abill under test should match the master pattern associated with theopposite side of a genuine bill identified by Match 1.

Alternatively, in situations where the face orientation of a bill (i.e.,whether a bill is “face up” or “face down”) may be determined prior toor during characteristic pattern scanning, the number of comparisons maybe reduced by limiting comparisons to patterns corresponding to the sameside of a bill. That is, for example, when it is known that a bill is“face up”, scanned patterns associated with scanheads above thetransport path need only be compared to master patterns generated byscanning the “face” of genuine bills. By “face” of a bill it is meant aside which is designated as the front surface of the bill. For example,the front or “face” of a U.S. bill may be designated as the “black”surface while the back of a U.S. bill may be designated as the “green”surface. The face orientation may be determinable in some situations bysensing the color of the surfaces of a bill. An alternative method ofdetermining the face orientation of U.S. bills by detecting theborderline on each side of a bill is described above in connection withFIGS. 6c, 6 d, and 12. The implementation of color sensing is discussedin more detailed below.

According to the embodiment of FIG. 42, the bill transport mechanismoperates in such a fashion that the central area C of a bill 1074 istransported between central scanheads 1072 b and 1072 e. Scanheads 1072a and 1072 c and likewise scanheads 1072 d and 1072 f are displaced thesame distance from central scanheads 1072 b and 1072 e, respectively. Bysymmetrically arranging the scanheads about the central region of abill, a bill may be scanned in either direction, e.g., top edge first(forward direction) or bottom edge first (reverse direction). Asdescribed above with respect to FIGS. 1-7b, master patterns are storedfrom the scanning of genuine bills in both the forward and reversedirections. While a symmetrical arrangement is preferred, it is notessential provided appropriate master patterns are stored for anon-symmetrical system.

While FIG. 42 illustrates a system having three scanheads per side, anynumber of scanheads per side may be utilized. Likewise, it is notnecessary that there be a scanhead positioned over the central region ofa bill. For example, FIG. 43 illustrates another embodiment of thepresent invention capable of scanning the segments S₁ and S₂ of FIG. 40.Scanheads 1076 a, 1076 d, 1076 e, and 1076 h scan a bill 1078 alongsegment S₁ while scanheads 1076 b, 1076 c, 1076 f, and 1076 g scansegment S₂.

FIG. 44 depicts another embodiment of a scanning system according to thepresent invention having laterally moveable scanheads 1080 a-b. Similarscanheads may be positioned on the opposite side of the transport path.Moveable scanheads 1080 a-b may provide more flexibility that may bedesirable in certain scanning situations. Upon the determination of thedimensions of a bill as described in connection with FIG. 39, apreliminary determination of the identity of a bill may be made. Basedon this preliminary determination, the moveable scanheads 1080 a-b maybe positioned over the area of the bill which is most appropriate forretrieving discrimination information. For example, if based on the sizeof a scanned bill, it is preliminarily determined that the bill is aJapanese 5000 Yen bill-type, and if it has been determined that asuitable characteristic pattern for a 5000 Yen bill-type is obtained byscanning a segment 2.0 cm to the left of center of the bill fed in theforward direction, scanheads 1080 a and 1080 b may be appropriatelypositioned for scanning such a segment, e.g., scanhead 1080 a positioned2.0 cm left of center and scanhead 1080 b positioned 2.0 cm right ofcenter. Such positioning permits proper discrimination regardless of thewhether the scanned bill is being fed in the forward or reversedirection. Likewise scanheads on the opposite side of the transport path(not shown) could be appropriately positioned. Alternatively, a singlemoveable scanhead may be used on one or both sides of the transportpath. In such a system, size and color information (to be described inmore detail below) may be used to properly position a single laterallymoveable scanhead, especially where the orientation of a bill may bedetermined before scanning.

FIG. 44 depicts a system in which the transport mechanism is designed todeliver a bill 1082 to be scanned centered within the area in whichscanheads 1080 a-b are located. Accordingly, scanheads 1080 a-b aredesigned to move relative to the center of the transport path withscanhead 1080 a being moveable within the range R₁ and scanhead 1080 bbeing moveable within range R₂.

FIG. 45 depicts another embodiment of a scanning system according to thepresent invention wherein bills to be scanned are transported in a leftjustified manner along the transport path, that is wherein the left edgeL of a bill 1084 is positioned in the same lateral location relative tothe transport path. Based on the dimensions of the bill, the position ofthe center of the bill may be determined and the scanheads 1086 a-b mayin turn be positioned accordingly. As depicted in FIG. 45, scanhead 1086a has a range of motion R₃ and scanhead 1086 b has a range of motion R₄.The ranges of motion of scanheads 1086 a-b may be influenced by therange of dimensions of bills which the discrimination system is designedto accommodate. Similar scanheads may be positioned on the opposite sideof the transport path.

Alternatively, the transport mechanism may be designed such that scannedbills are not necessarily centered or justified along the lateraldimension of the transport path. Rather the design of the transportmechanism may permit the position of bills to vary left and right withinthe lateral dimension of the transport path. In such a case, the edgesensors 1066 of FIG. 39 may be used to locate the edges and center of abill, and thus provide positional information in a moveable scanheadsystem and selection criteria in a stationary scanhead system.

In addition to the stationary scanhead and moveable scanhead systemsdescribed above, a hybrid system having both stationary and moveablescanheads may be used. Likewise, it should be noted that the laterallydisplaced scanheads described above need not lie along the same lateralaxis. That is, the scanheads may be, for example, staggered upstream anddownstream from each other. FIG. 46 is a top view of a staggeredscanhead arrangement according to one embodiment of the presentinvention. As illustrated in FIG. 46, a bill 1130 is transported in acentered manner along the transport path 1132 so that the center 1134 ofthe bill 1130 is aligned with the center 1136 of the transport path1132. Scanheads 1140 a-h are arranged in a staggered manner so as topermit scanning of the entire width of the transport path 1132. Theareas illuminated by each scanhead are illustrated by strips 1142 a,1142 b, 1142 e, and 1142 f for scanheads 1140 a, 1140 b, 1140 e, and1140 f, respectively. Based on size determination sensors, scanheads1140 a and 1140 h may either not be activated or their output ignored.

In general, if prior to scanning a document, preliminary informationabout a document can be obtained, such as its size or color,appropriately positioned stationary scanheads may be activated orlaterally moveable scanheads may be appropriately positioned providedthe preliminary information provides some indication as to the potentialidentity of the document. Alternatively, especially in systems havingscanheads positioned over a significant portion of the transport path,many or all of the scanheads of a system may be activated to scan adocument. Then subsequently, after some preliminary determination as toa document's identity has been made, only the output or derivationsthereof of appropriately located scanheads may be used to generatescanned patterns. Derivations of output signals include, for example,data samples stored in memory generated by sampling output signals.Under such an alternative embodiment, information enabling a preliminarydetermination as to a document's identity may be obtained by analyzinginformation either from sensors separate from the scanheads or from oneor more of the scanheads themselves. An advantage of such preliminarydeterminations is that the number of scanned patterns which have to begenerated or compared to a set of master patterns is reduced. Likewisethe number of master patterns to which scanned patterns must be comparedmay also be reduced.

While the scanheads 1140 a-h of FIG. 46 are arranged in anon-overlapping manner, they may alternatively be arranged in anoverlapping manner. By providing additional lateral positions, anoverlapping scanhead arrangement may provide greater selectivity in thesegments to be scanned. This increase in scanable segments may bebeneficial in compensating for currency manufacturing tolerances whichresult in positional variances of the printed indicia on bills relativeto their edges. Additionally, in one embodiment, scanheads positionedabove the transport path are positioned upstream relative to theircorresponding scanheads positioned below the transport path.

FIGS. 47a and 47 b illustrate another embodiment of the present ininvention wherein a plurality of analog sensors 1150 such asphotodetectors are laterally displaced from each other and are arrangedin a linear array within a single scanhead 1152. FIG. 47a is a top viewwhile FIG. 47b is a side elevation view of such a linear arrayembodiment. The output of individual sensors 1150 are connected toanalog-to-digital converters (not shown) through the use of graded indexfibers, such as a “lens array” manufactured by MSG America, Inc., partnumber SLA20A1675702A3, and subsequently to a CPU (not shown) in amanner similar to that depicted in FIGS. 1 and 6a. As depicted in FIGS.47a and 47 b, a bill 1154 is transported past the linear array scanhead1152 in a centered fashion. One length for the linear array scanhead isabout 6-7 inches (15 cm-17 cm).

In a manner similar to that described above, based on the determinationof the size of a bill, appropriate sensors may be activated and theiroutput used to generate scanned patterns. Alternatively many or all ofthe sensors may be activated with only the output or derivations thereofof appropriately located sensors being used to generate scannedpatterns. Derivations of output signals include, for example, datasamples stored in memory generated by sampling output signals. As aresult, a discriminating system incorporating a linear array scanheadaccording the present invention would be capable of accommodating a widevariety of bill-types. Additionally, a linear array scanhead provides agreat deal of flexibility in how information may be read and processedwith respect to various bills. In addition to the ability to generatescanned patterns along segments in a direction parallel to the directionof bill movement, by appropriately processing scanned samples, scannedpatterns may be “generated” or approximated in a direction perpendicularto the direction of bill movement. For example, if the linear arrayscanhead 1152 comprises one hundred and sixty (160) sensors 1150 over alength of 7 inches (17.78 cm) instead of taking samples for 64 encoderpulses from say 30 sensors, samples may be taken for 5 encoder pulsesfrom all 160 cells (or all those positioned over the bill 1154).Alternatively, 160 scanned patterns (or selected ones thereof) of 5 datasamples each may be used for pattern comparisons. Accordingly, it can beseen that the data acquisition time is significantly reduced from 64encoder pulses to only 5 encoder pulses. The time saved in acquiringdata can be used to permit more time to be spent processing data and/orto reduce the total scanning time per bill thus enabling increasedthroughput of the identification system. Additionally, the linear arrayscanhead permits a great deal of flexibility in tailoring the areas tobe scanned. For example, it has been found that the leading edge ofCanadian bills contain valuable graphic information. Accordingly, whenit is determined that a test bill may be a Canadian bill (or when theidentification system is set to a Canadian currency setting), thescanning area can be limited to the leading edge area of bills, forexample, by activating many laterally displaced sensors for a relativelyfew number of encoder pulses.

FIG. 48 is a top view of another embodiment of a linear array scanhead1170 having a plurality of analog sensors 1172 such as photodetectorswherein a bill 1174 is transported past the scanhead 1170 in anon-centered manner. As discussed above, positional information fromsize determining sensors may be used to select appropriate sensors.Alternatively, the linear array scanhead itself may be employed todetermine the size of a bill, thus eliminating the need for separatesize determining sensors. For example, all sensors may be activated,data samples derived from sensors located on the ends of the lineararray scanhead may be preliminarily processed to determine the lateralposition and the length of a bill. The width of a bill may be determinedeither by employing separate leading/trailing edge sensors orpre-processing data samples derived from initial and ending cycleencoder pulses. Once size information is obtained about a bill undertest, only the data samples retrieved from appropriate areas of a billneed be further processed.

FIG. 49 is a top view of another embodiment of a linear scanhead 1180according to the present invention illustrating the ability tocompensate for skewing of bills. Scanhead 1180 has a plurality of analogsensors 1182 and a bill 1184 is transported past scanhead 1180 in askewed manner. Once the skew of a bill has been determined, for examplethrough the use of leading edge sensors, readings from sensors 1182along the scanhead 1180 may be appropriately delayed. For example,suppose it is determined that a bill is being fed past scanhead 1180 sothat the left front corner of the bill reaches the scanhead five encoderpulses before the right front corner of the bill. In such a case, sensorreadings along the right edge of the bill can be delayed for 5 encoderpulses to compensate for the skew. Where scanned patterns are to begenerated over only a few encoder pulses, the bill may be treated asbeing fed in a non-skewed manner since the amount of lateral deviationbetween a scan along a skewed angle and a scan along a non-skewed angleis minimal for a scan of only a few encoder pulses. However, where it isdesired to obtain a scan over a large number of encoder pulses, a singlescanned pattern may be generated from the outputs of more than onesensor. For example, a scanned pattern may be generated by taking datasamples from sensor 1186 a for a given number of encoder pulses, thentaking data samples from sensor 1186 b for a next given number ofencoder pulses, and then taking data samples from sensor 1186 c for anext given number of encoder pulses. The number of given encoder pulsesfor which data samples may be taken from the same sensor is influencedby the degree of skew, the greater the degree of skew of the bill, thefewer the number of data samples which may be obtained before switchingto the next sensor. Alternatively, master patterns may be generated andstored for various degrees of skew, thus permitting a single sensor togenerate a scanned pattern from a bill under test.

With regards to FIGS. 47-49, while only a single linear array scanheadis shown, another linear array scanhead may be positioned on theopposite side of the transport path to permit scanning of either or bothsides of a bill. Likewise, the benefits of using a linear array scanheadmay also be obtainable using a multiple scanhead arrangement which isconfigured appropriately, for example such as depicted in FIG. 46 or alinear arrangement of multiple scanheads.

In addition to size and scanned characteristic patterns, color may alsobe used to discriminate bills. For example, while all U.S. bills areprinted in the same colors, e.g., a green side and a black side, billsfrom other countries often vary in color with the denomination of thebill. For example, a German 50 deutsche mark bill-type is brown in colorwhile a German 100 deutsche mark bill-type is blue in color.Alternatively, color detection may be used to determine the faceorientation of a bill, such as where the color of each side of a billvaries. For example, color detection may be used to determine the faceorientation of U.S. bills by detecting whether or not the “green” sideof a U.S. bill is facing upwards. Separate color sensors may be addedupstream of the scanheads described above. According to such anembodiment, color information may be used in addition to sizeinformation to preliminarily identify a bill. Likewise, colorinformation may be used to determine the face orientation of a billwhich determination may be used to select upper or lower scanheads forscanning a bill accordingly or compare scanned patterns retrieved fromupper scanheads with a set of master patterns generated by scanning acorresponding face while the scanned patterns retrieved from the lowerscanheads are compared with a set of master patterns generated byscanning an opposing face. Alternatively, color sensing may beincorporated into the scanheads described above. Such color sensing maybe achieved by, for example, incorporating color filters, colored lightsources, and/or dichroic beamsplitters into the currency discriminationsystem of the present invention. Color information acquisition isdescribed in more detail in co-pending U.S. application Ser. No.08/219,093 filed Mar. 29, 1994, for a “Currency Discriminator andAuthenticator” incorporated herein by reference. Various colorinformation acquisition techniques are described in U.S. Pat. Nos.4,841,358; 4,658,289; 4,716,456; 4,825,246; and 4,992,860.

The operation of a currency discriminator according to one embodiment ofthe present invention may be further understood by referring to theflowchart of FIGS. 50a and 50 b. In the process beginning at step 1100,a bill is fed along a transport path (step 1102) past sensors whichmeasure the length and width of the bill (step 1104). These sizedetermining sensors may be, for example, those illustrated in FIG. 39.Next at step 1106, it is determined whether the measured dimensions ofthe bill match the dimensions of at least one bill stored in memory,such as EPROM 60 of FIG. 7a. If no match is found, an appropriate erroris generated at step 1108. If a match is found, the color of the bill isscanned for at step 1110. At step 1112, it is determined whether thecolor of the bill matches a color associated with a genuine bill havingthe dimensions measured at step 1104. An error is generated at step 1114if no such match is found. However, if a match is found, a preliminaryset of potentially matching bills is generated at step 1116. Often, onlyone possible identity will exist for a bill having a given color anddimensions. However, the preliminary set of step 1116 is not limited tothe identification of a single bill-type, that is, a specificdenomination of a specific currency system; but rather, the preliminaryset may comprise a number of potential bill-types. For example, all U.S.bills have the same size and color. Therefore, the preliminary setgenerated by scanning a U.S. $5 bill would include U.S. bills of alldenominations.

Based on the preliminary set (step 1116), selected scanheads in astationary scanhead system may be activated (step 1118). For example, ifthe preliminary identification indicates that a bill being scanned hasthe color and dimensions of a German 100 deutsche mark, the scanheadsover regions associated with the scanning of an appropriate segment fora German 100 deutsche mark may be activated. Then upon detection of theleading edge of the bill by sensors 1068 of FIG. 40, the appropriatesegment may be scanned. Alternatively, all scanheads may be active withonly the scanning information from selected scanheads being processed.Alternatively, based on the preliminary identification of a bill (step1116), moveable scanheads may be appropriately positioned (step 1118).

Subsequently, the bill is scanned for a characteristic pattern (step1120). At step 1122, the scanned patterns produced by the scanheads arecompared with the stored master patterns associated with genuine billsas dictated by the preliminary set. By only making comparisons withmaster patterns of bills within the preliminary set, processing time maybe reduced. Thus for example, if the preliminary set indicated that thescanned bill could only possibly be a German 100 deutsche mark, thenonly the master pattern or patterns associated with a German 100deutsche mark need be compared to the scanned patterns. If no match isfound, an appropriate error is generated (step 1124). If a scannedpattern does match an appropriate master pattern, the identity of thebill is accordingly indicated (step 1126) and the process is ended (step1128).

While some of the embodiments discussed above entailed a system capableof identifying a plurality of bill-types, the system may be adapted toidentify a bill under test as either belonging to a specific bill-typeor not. For example, the system may be adapted to store masterinformation associated with only a single bill-type such as a UnitedKingdom 5 pound bill. Such a system would identify bills under testwhich were United Kingdom 5 pound bills and would reject all otherbill-types.

The scanheads of the present invention may be incorporated into adocument identification system capable of identifying a variety ofdocuments. For example, the system may be designed to accommodate anumber of currencies from different countries. Such a system may bedesigned to permit operation in a number of modes. For example, thesystem may be designed to permit an operator to select one or more of aplurality of bill-types which the system is designed to accommodate.Such a selection may be used to limit the number of master patterns withwhich scanned patterns are to be compared. Likewise, the operator may bepermitted to select the manner in which bills will be fed, such as allbills face up, all bills top edge first, random face orientation, and/orrandom top edge orientation. Additionally, the system may be designed topermit output information to be displayed in a variety of formats to avariety of peripherals, such as a monitor. LCD display, or printer. Forexample, the system may be designed to count the number of each specificbill-types identified and to tabulate the total amount of currencycounted for each of a plurality of currency systems. For example, astack of bills could be placed in the bill accepting station 12 of FIGS.2a-2 b, and the output unit 36 of FIGS. 2a-2 b may indicate that a totalof 370 British pounds and 650 German marks were counted. Alternatively,the output from scanning the same batch of bills may provide moredetailed information about the specific denominations counted, forexample one 100 pound bill, five 50 pound bills, and one 20 pound billand thirteen 50 deutsche mark bills. Such a device would be useful in abank teller environment. A bank customer could hand the teller the abovestack of bills. The teller could then place the stack of bills in thedevice. The device quickly scans the bills and indicates that a total of370 British pounds and 650 German marks were counted. The teller couldthen issue the customer a receipt. At some point after the abovetransaction, the teller could separate the bills either by hand and/orby using an automatic sorter device located, for example, in a backroom. The above transaction could then be performed rapidly without thecustomer being detained while the bills are being sorted.

In a document identification system capable of identifying a variety ofbills from a number of countries, a manual selection device, such as aswitch or a scrolling selection display, may be provided so that theoperator may designate what type of currency is to be discriminated. Forexample, in a system designed to accommodate both Canadian and Germancurrency, the operator could turn a dial to the Canadian bill setting orscroll through a displayed menu and designate Canadian bills. Bypre-declaring what type of currency is to be discriminated, scannedpatterns need only be compared to master patterns corresponding to theindicated type of currency, e.g., Canadian bills. By reducing the numberof master patterns which have to be compared to scanned patterns, theprocessing time can be reduced.

Alternatively, a system may be designed to compare scanned patterns toall stored master patterns. In such a system, the operator need notpre-declare what type of currency is to be scanned. This reduces thedemands on the operator of the device. Furthermore, such a system wouldpermit the inputting of a mixture of bills from a number of countries.The system would scan each bill and automatically determine the issuingcountry and the denomination.

In addition to the manual and automatic bill-type discriminatingsystems, an alternate system employs a semi-automatic bill-typediscriminating method. Such a system would work in a manner similar tothe stranger mode described above. In such a system, a stack of bills isplaced in the input hopper. The first bill is scanned and the generatedscanned pattern is compared with the master patterns associated withbills from a number of different countries. The discriminator identifiesthe country-type and the denomination of the bill. Then thediscriminator compares all subsequent bills in the stack to the masterpatterns associated with bills only from the same country as the firstbill. For example, if a stack of U.S. bills were placed in the inputhopper and the first bill was a $5 bill, the first bill would bescanned. The scanned pattern would be compared to master patternsassociated with bills from a number of countries, e.g., U.S., Canadian,and German bills. Upon determining that the first bill is a U.S. $5bill, scanned patterns from the remaining bills in the stack arecompared only to master patterns associated with U.S. bills, e.g., $1,$2, $5, $10, $20, $50, and $100 bills. When a bill fails to sufficientlymatch one of the compared patterns, the bill may be flagged as describedabove such as by stopping the transport mechanism with the flagged billbeing the last bill deposited in the output receptacle.

A currency discriminating device designed to accommodate both Canadianand German currency bills will now be described. According to thisembodiment, a currency discriminating device similar to that describedabove in connection with scanning U.S. currency (see, e.g., FIGS. 1-38and accompanying description) is modified so as to be able to acceptboth Canadian and German currency bills. According to one embodimentwhen Canadian bills are being discriminated, no magnetic sampling orauthentication is performed.

Canadian bills have one side with a portrait (the portrait side) and areverse side with a picture (the picture side). Likewise, German billsalso have one side with a portrait (the portrait side) and a reverseside with a picture (the picture side). In one embodiment, thediscriminator is designed to accept either stacks of Canadian bills orstacks of German bills, the bills in the stacks being faced so that thepicture side of all the bills will be scanned by a triple scanheadarrangement to be described in connection with FIG. 51. In oneembodiment, this triple scanhead replaces the single scanheadarrangement housed in the unitary molded plastic support member 280(see, e.g., FIGS. 25 and 26).

FIG. 51 is a top view of a triple scanhead arrangement 1200. The triplescanhead arrangement 1200 comprises a center scanhead 1202, a leftscanhead 1204, and a right scanhead 1206 housed in a unitary moldedplastic support member 1208. A bill 1210 passes under the arrangement1200 in the direction shown. O-rings are positioned near each scanhead,preferably two O-rings per scanhead, one on each side of a respectivescanhead, to engage the bill continuously while transporting the billbetween rolls 223 and 241 (FIG. 20a) and to help hold the bill flatagainst the guide plate 240 (FIG. 20a). The left 1204 and right 1206scanhead are placed slightly upstream of the center scanhead 1202 by adistance D₃. In one embodiment, D₃ is 0.083 inches (0.21 cm). The centerscanhead 1202 is centered over the center C of the transport path 1216.The center L_(C) of the left scanhead 1204 and the center R_(C) of theright scanhead 1206 are displaced laterally from center C of thetransport path in a symmetrical fashion by a distance D₄. In oneembodiment D₄ is 1.625 inches (4.128 cm).

The scanheads 1202, 1204, and 1206 are each similar to the scanheadsdescribe above connection with FIGS. 1-38, except only a wide slithaving a length of about 0.500″ and a width of about 0.050″ is utilized.The wide slit of each scanhead is used both to detect the leading edgeof a bill and to scan a bill after the leading edge has been detected.

Two photosensors 1212 and 1214 are located along the lateral axis of theleft and right scanheads 1204 and 1206, one on either side of the centerscanhead 1202. Photosensors 1212 and 1214 are same as the photosensorsPS1 and PS2 describe above (see, e.g., FIGS. 26 and 30). Photosensors1212 and 1214 are used to detect doubles and also to measure thedimension of bills in the direction of bill movement which in theembodiment depicted in FIG. 51 is the narrow dimension of bills.Photosensors 1212 and 1214 are used to measure the narrow dimension of abill by indicating when the leading and trailing edges of a bill passesby the photosensors 1212 and 1214. This information in combination withthe encoder information permits the narrow dimension of a bill to bemeasured.

All Canadian bills are 6″ (15.24 cm) in their long dimension and 2.75″(6.985 cm) in their narrow dimension. German bills vary in sizeaccording to denomination. In one embodiment of the currencydiscriminating system, the discriminating device is designed to acceptand discriminate $2, $5, $10, $20, $50, and $100 Canadian bills and 10DM, 20 DM, 50 DM, and 100 DM German bills. These German bills vary insize from 13.0 cm (5.12″) in the long dimension by 6.0 cm (2.36″) in thenarrow dimension for 10 DM bills to 16.0 cm (6.30″) in the longdimension by 8.0 cm (3.15″) in the narrow dimension for 100 DM bills.The input hopper of the discriminating device is made sufficiently wideto accommodate all the above listed Canadian and German bills, e.g.,6.3″ (16.0 cm) wide.

FIG. 52 is a top view of a Canadian bill illustrating the areas scannedby the triple scanhead arrangement of FIG. 51. In generating scannedpatterns from a Canadian bill 1300 traveling along a transport path1301, segments SL₁, SC₁, and SR₁ are scanned by the left 1204, center1202, and right 1206 scanheads, respectively, on the picture side of thebill 1300. These segments are similar to segment S in FIG. 4. Eachsegment begins a predetermined distance D₅ inboard of the leading edgeof the bill. In one embodiment D₅ is 0.5″ (1.27 cm). Segments SL₁, SC₁,and SR₁, each comprise 64 samples as shown in FIGS. 3 and 5. In oneembodiment Canadian bills are scanned at a rate of 1000 bills perminute. The lateral location of segments SL₁, SC₁, and SR₁ is fixedrelative to the transport path 1301 but may vary left to right relativeto bill 1300 since the lateral position of bill 1300 may vary left toright within the transport path 1301.

A set of eighteen (18) master Canadian patterns are stored for each typeof Canadian bill that the system is designed to discriminate, three (3)for each scanhead in both the forward and reverse directions. Forexample, three patterns are generated by scanning a given genuineCanadian bill in the forward direction with the center scanhead. Onepattern is generated by scanning down the center of the bill alongsegment SC₁, a second is generated by scanning along a segment SC₂initiated 1.5 samples before the beginning of SC₁, and a third isgenerated by scanning along a segment SC₃ initiated 1.5 samples afterthe beginning of SC₁. The second and third patterns are generated tocompensate for the problems associated with triggering off the edge of abill as discussed above.

To compensate for possible lateral displacement of bills to be scannedalong a direction transverse to the direction of bill movement, theexact lateral location along which each of the above master patterns isgenerated is chosen after considering the correlation results achievedwhen a bill is displaced slightly to the left or to the right of thecenter of each scanhead, i.e., lines L_(C), S_(C), and R_(C). Forexample, in generating a master pattern associated with segment SC₁, ascan of a genuine bill may be taken down the center of a bill, a secondscan may be taken along a segment 0.15″ to the right of center (+0.15″),and a third scan may be taken along a segment 0.15″ to the left ofcenter (−0.15″). Based on the correlation result achieved, the actualscan location may be adjusted slightly to the right or left so theeffect of the lateral displacement of a bill on the correlation resultsis minimized. Thus, for example, the master pattern associated with aforward scan of a Canadian $2 bill using the center scanhead 1202 may betaken along a line 0.05″ to the right of the center of the bill.

Furthermore, the above stored master patterns are generated either byscanning both a relatively new crisp genuine bill and an older yellowedgenuine bill and averaging the patterns generated from each or,alternatively, by scanning an average looking bill.

Master patterns are stored for nine (9) types of Canadian bills, namely,the newer series $2, $5, $10, $20, $50, and $100 bills and the olderseries $20, $50, and $100 bills. Accordingly, a total of 162 Canadianmaster patterns are stored (9 types×18 per type).

FIG. 53 is a flowchart of the threshold test utilized in calling thedenomination of a Canadian bill. When Canadian bills are beingdiscriminated the flowchart of FIG. 53 replaces the flowchart of FIG.13. The correlation results associated with correlating a scannedpattern to a master pattern of a given type of Canadian bill in a givenscan direction and a given offset in the direction of bill movement fromeach of the three scanheads are summed. The highest of the resulting 54summations is designated the #1 correlation and the second highest ispreliminarily designated the #2 correlation. The #1 and #2 correlationseach have a given bill type associated with them. If the bill typeassociated with the #2 correlation is merely a different series from,but the same denomination as, the bill type associated with the #1denomination, the preliminarily designated #2 correlation is substitutedwith the next highest correlation where the bill denomination isdifferent from the denomination of the bill type associated with the #1correlation.

The threshold test of FIG. 53 begins at step 1302. Step 1304 checks thedenomination associated with the #1 correlation. If the denominationassociated with the #1 correlation is not a $50 or $100, the #1correlation is compared to a threshold of 1900 at step 1306. If the #1correlation is less than or equal to 1900, the correlation number is toolow to identify the denomination of the bill with certainty. Therefore,step 1308 sets a “no call” bit in a correlation result flag and thesystem returns to the main program at step 1310. If, however, the #1correlation is greater than 1900 at step 1306, the system advances tostep 1312 which determines whether the #1 correlation is greater than2000. If the #1 correlation is greater than 2000, the correlation numberis sufficiently high that the denomination of the scanned bill can beidentified with certainty without any further checking. Consequently, a“good call” bit is set in the correlation result flag at step 1314 andthe system returns to the main program at step 1310.

If the #1 correlation is not greater than 2000 at step 1312, step 1316checks the denomination associated with the #2 correlation. If thedenomination associated with the #2 correlation is not a $50 or $100,the #2 correlation is compared to a threshold of 1900 at step 1318. Ifthe #2 correlation is less than or equal to 1900, the denominationidentified by the #1 correlation is acceptable, and thus the “good call”bit is set in the correlation result flag at step 1314 and the systemreturns to the main program at step 1310. If, however, the #2correlation is greater than 1900 at step 1318, the denomination of thescanned bill cannot be identified with certainty because the #1 and #2correlations are both above 1900 and, yet, are associated with differentdenominations. Accordingly, the “no call” bit is set in the correlationresult flag at step 1308.

If the denomination associated with the #2 correlation is a $50 or $100at step 1316, the #2 correlation is compared to a threshold of 1500 atstep 1320. If the #2 correlation is less than or equal to 1500, thedenomination identified by the #1 correlation is acceptable, and thusthe “good call” bit is set in the correlation result flag at step 1314and the system returns to the main program at step 1310. If, however,the #2 correlation is greater than 1500 at step 1320, the denominationof the scanned bill cannot be identified with certainty. As a result,the “no call” bit is set in the correlation result flag at step 1308.

If the denomination associated with the #1 correlation is a $50 or $100at step 1304, the #1 correlation is compared to a threshold of 1500 atstep 1322. If the #1 correlation is less than or equal to 1500, thedenomination of the scanned bill cannot be identified with certaintyand, therefore, the “no call” bit is set in the correlation result flagat step 1308. If, however, the #1 correlation at step 1322 is greaterthan 1500, the system advances to step 1312 which determines whether the#1 correlation is greater than 2000. If the #1 correlation is greaterthan 2000, the correlation number is sufficiently high that thedenomination of the scanned bill can be identified with certaintywithout any further checking. Consequently, a “good call” bit is set inthe correlation result flag at step 1314 and the system returns to themain program at step 1310.

If the #1 correlation is not greater than 2000 at step 1312, step 1316checks the denomination associated with the #2 correlation. If thedenomination associated with the #2 correlation is not a $50 or $100,the #2 correlation is compared to a threshold of 1900 at step 1318. Ifthe #2 correlation is less than or equal to 1900, the denominationidentified by the #1 correlation is acceptable, and thus the “good call”bit is set in the correlation result flag at step 1314 and the systemreturns to the main program at step 1310. If, however, the #2correlation is greater than 1900 at step 1318, the denomination of thescanned bill cannot be identified with certainty. Accordingly, the “nocall” bit is set in the correlation result flag at step 1308.

If the denomination associated with the #2 correlation is a $50 or $100at step 1316, the #2 correlation is compared to a threshold of 1500 atstep 1320. If the #2 correlation is less than or equal to 1500, thedenomination identified by the #1 correlation is acceptable, and thusthe “good call” bit is set in the correlation result flag at step 1314and the system returns to the main program at step 1310. If, however,the #2 correlation is greater than 1500 at step 1320, the denominationof the scanned bill cannot be identified with certainty. As a result,the “no call” bit is set in the correlation result flag at step 1308 andthe system returns to the main program at step 1310.

Now the use of the triple scanhead arrangement 1200 in scanning anddiscriminating German currency will be described. When scanning Germanbills, only the output of the center scanhead 1202 is utilized togenerate scanned patterns. A segment similar to segment S of FIG. 4 isscanned over the center of the transport path at a predetermineddistance D₆ inboard after the leading edge of a bill is detected. In oneembodiment D₆ is 0.25′ (0.635 cm). The scanned segment comprises 64samples as shown in FIGS. 3 and 5. In one embodiment German bills arescanned at a rate of 1000 bills per minute. The lateral location of thescanned segment is fixed relative to the transport path 1216 but mayvary left to right relative to bill 1210 since the lateral position ofbill 1210 may vary left to right within the transport path 1216.

FIG. 54a illustrates the general areas scanned in generating master 10DM German patterns. Due to the short length of 10 DM bills in their longdimension relative to the width of the transport path, thirty (30) 10 DMmaster patterns are stored. A first set of five patterns are generatedby scanning a genuine 10 DM bill 1400 in the forward direction alonglaterally displaced segments all beginning a predetermined distance D₆inboard of the leading edge of the bill 1400. Each of these fivelaterally displaced segments is centered about a respective one of linesL₁-L₅. One such segment S10 ₁ centered about line L₁ is illustrated inFIG. 54a. Line L₁ is disposed down the center C of the bill 1400. In oneembodiment lines L₂-L₅ are disposed in a symmetrical fashion about thecenter C of the bill 1400. In one embodiment lines L₂ and L₃ arelaterally displaced from L₁ by a distance D₇ where D₇ is 0.24″ (0.61 cm)and lines L₄ and L₅ are laterally displaced from L₁ by a distance D₈where D₈ is 0.48″ (1.22 cm).

A second set of five patterns are generated by scanning a genuine 10 DMbill 1400 in the forward direction along laterally displaced segmentsalong lines L₁-L₅ all beginning at a second predetermined distanceinboard of the leading edge of the bill 1400, the second predetermineddistance being less than the predetermined distance D₆. One such segmentS10 ₂ centered about line L₁ is illustrated in FIG. 54a. In oneembodiment the second predetermined distance is such that scanningbegins one sample earlier than D₆, that is about 30 mils before theinitiation of the patterns in the first set of five patterns.

A third set of five patterns are generated by scanning a genuine 10 DMbill 1400 in the forward direction along laterally displaced segmentsalong lines L₁-L₅ all beginning at a third predetermined distanceinboard of the leading edge of the bill 1400, the third predetermineddistance being greater than the predetermined distance D₆. One suchsegment S10 ₃ centered about line L₁ is illustrated in FIG. 54a. In oneembodiment the third predetermined distance is such that scanning beginsone sample later than D₆, that is about 30 mils after the initiation ofthe patterns in the first set of five patterns.

The above three sets of five patterns yield fifteen patterns in theforward direction. Fifteen additional 10 DM master patterns taken in themanner described above but in the reverse direction are also stored.

FIG. 54b illustrates the general areas scanned in generating master 20DM, 50 DM, and 100 DM German patterns. Due to the lengths of 20 DM, 50DM, and 100 DM bills in their long dimension being shorter than thewidth of the transport path, eighteen (18) 20 DM master patterns,eighteen (18) 50 DM master patterns, and eighteen (18) 100 DM masterpatterns are stored. The 50 DM master patterns and the 100 DM masterpatterns are taken in the same manner as the 20 DM master patternsexcept that the 50 DM master patterns and 100 DM master patterns aregenerated from respective genuine 50 DM bills and 100 DM bills while the20 DM master patterns are generated from genuine 20 DM bills. Therefore,only the generation of the 20 DM master patterns will be described indetail.

A first set of three patterns are generated by scanning a genuine 20 DMbill 1402 in the forward direction along laterally displaced segmentsall beginning a predetermined distance D₆ inboard of the leading edge ofthe bill 1402. Each of these three laterally displaced segments iscentered about a respective one of lines L₆-L₈. One such segment S20 ₁centered about line L₆ is illustrated in FIG. 54b. Line L₆ is disposeddown the center C of the bill 1402. In one embodiment lines L₁-L₈ aredisposed in a symmetrical fashion about the center C of the bill 1402.In one embodiment lines L₇ and L₈ are laterally displaced from L₆ by adistance D₉ where D₉ is 0.30″ (0.76 cm) for the 20 DM bill. The value ofD₉ is 0.20″ (0.51 cm) for the 50 DM bill and 0.10″ (0.25 cm) for the 100DM bill.

A second set of three patterns are generated by scanning a genuine 20 DMbill 1402 in the forward direction along laterally displaced segmentsalong lines L₆-L₈ all beginning at a second predetermined distanceinboard of the leading edge of the bill 1402, the second predetermineddistance being less than the predetermined distance D₆. One such segmentS20 ₂ centered about line L₆ is illustrated in FIG. 54b. In oneembodiment the second predetermined distance is such that scanningbegins one sample earlier than D₆, that is about 30 mils before theinitiation of the patterns in the first set of three patterns.

A third set of three patterns are generated by scanning a genuine 20 DMbill 1402 in the forward direction along laterally displaced segmentsalong lines L₆-L₈ all beginning at a third predetermined distanceinboard of the leading edge of the bill 1402, the third predetermineddistance being greater than the predetermined distance D₆. One suchsegment S20 ₃ centered about line L₆ is illustrated in FIG. 54b. In oneembodiment the third predetermined distance is such that scanning beginsone sample later than D₆, that is about 30 mils after the initiation ofthe patterns in the first set of three patterns.

The above three sets of three patterns yield nine patterns in theforward direction. Nine additional 20 DM master patterns taken in themanner described above but in the reverse direction are also stored.Furthermore, the above stored master patterns are generated either byscanning both a relatively new crisp genuine bill and an older yellowedgenuine bill and averaging the patterns generated from each or,alternatively, by scanning an average looking bill.

This yields a total of 84 German master patterns (30 for 10 DM bills, 18for 20 DM bills, 18 for 50 DM bills, and 18 for 100 DM bills). To reducethe number of master patterns that must compared to a given scannedpattern, the narrow dimension of a scanned bill is measured usingphotosensors 1212 and 1214. After a given bill has been scanned by thecenter scanhead 1202, the generated scanned pattern is correlated onlyagainst certain ones of above described 84 master patterns based on thesize of the narrow dimension of the bill as determined by thephotosensors 1212 and 1214. The narrow dimension of each bill ismeasured independently by photosensors 1212 and 1214 and then averagedto indicate the length of the narrow dimension of a bill. In particular,a first number of encoder pulses occur between the detection of theleading and trailing edges of a bill by the photosensor 1212. Likewise,a second number of encoder pulses occur between the detection of theleading and trailing edges of the bill by the photosensor 1214. Thesefirst and second numbers of encoder pulses are averaged to indicate thelength of the narrow dimension of the bill in terms of encoder pulses.

The photosensors 1212 and 1214 can also determine the degree of skew ofa bill as it passes by the triple scanhead arrangement 1200. By countingthe number of encoder pulses between the time when photosensors 1212 and1214 detect the leading edge of a bill, the degree of skew can bedetermined in terms of encoder pulses. If no or little skew is measured,a generated scanned pattern is only compared to master patternsassociated with genuine bills having the same narrow dimension length.If a relatively large degree of skew is detected, a scanned pattern willbe compared with master patterns associated with genuine bills havingthe next smaller denominational amount than would be indicated by themeasured narrow dimension length.

Table 4 indicates which denominational set of master patterns are chosenfor comparison to the scanned pattern based on the measured narrowdimension length in terms of encoder pulses and the measured degree ofskew in terms of encoder pulses:

TABLE 4 Narrow Dimension Degree of Skew in Selected Set of Master Lengthin Encoder Pulses Encoder Pulses Patterns <1515 Not applicable 10 DM≧1515 and <1550 ≧175 10 DM ≧1515 and <1550 <175 20 DM ≧1550 and <1585≧300 10 DM ≧1550 and <1585 <300 20 DM ≧1585 and <1620 ≧200 20 DM ≧1585and <1620 <200 50 DM ≧1620 and <1655 ≧300 20 DM ≧1620 and <1655 <300 50DM ≧1655 and <1690 ≧150 50 DM ≧1655 and <1690 <150 100 DM ≧1690 and<1725 ≧300 50 DM ≧1690 and <1725 <300 100 DM ≧1725 Not applicable 100 DM

FIG. 55 is a flowchart of the threshold test utilized in calling thedenomination of a German bill. It should be understood that thisthreshold test compares the scanned bill pattern only to the set ofmaster patterns selected in accordance with Table 4. Therefore, theselection made in accordance with Table 4 provides a preliminaryindication as to the denomination of the scanned bill. The thresholdtest in FIG. 55, in effect, serves to confirm or overturn thepreliminary indication given by Table 4.

The threshold test of FIG. 55 begins at step 1324. Step 1326 checks thenarrow dimension length of the scanned bill in terms of encoder pulses.If the narrow dimension length is less than 1515 at step 1326, thepreliminary indication is that the denomination of the scanned bill is a10 DM bill. In order to confirm this preliminary indication, the #1correlation is compared to 550 at step 1328. If the #1 correlation isgreater than 550, the correlation number is sufficiently high toidentify the denomination of the bill as a 10 DM bill. Accordingly, a“good call” bit is set in a correlation result flag at step 1330, andthe system returns to the main program at step 1332. If, however, the #1correlation is less than or equal to 550 at step 1328, the preliminaryindication that the scanned bill is a 10 DM bill is effectivelyoverturned. The system advances to step 1334 which sets a “no call” bitin the correlation result flag.

If step 1326 determines that the narrow dimension length is greater thanor equal to 1515, a correlation threshold of 800 is required to confirmthe preliminary denominational indication provided by Table 4.Therefore, if the #1 correlation is greater than 800 at step 1336, thepreliminary indication provided by Table 4 is confirmed. To confirm thepreliminary indication, the “good call” bit is set in the correlationresult flag. If, however, the #1 correlation is less than or equal to800 at step 1336, the preliminary indication is rejected and the “nocall” bit in the correlation result flag is set at step 1334. The systemthen returns to the main program at step 1332.

According to one embodiment, the operator of the above describedcurrency discriminating device designed to accommodate both Canadian andGerman currency bills pre-declares whether Canadian or German bills areto be discriminated. By depressing an appropriate key on the keypad 62(FIG. 59), the display 63 will scroll through five different modes: acount mode, a Canadian stranger mode, a Canadian mixed mode, a Germanstranger mode, and a German mixed mode. In the count mode, the deviceacts like a simply bill counter (counting the number of bills in a stackbut not discriminating them by denomination). Canadian stranger mode issimilar to the stranger mode described below in connection with FIG. 59but bills are scanned as described above in connection with FIG. 52 andscanned patterns are correlated against Canadian master patterns.Likewise, Canadian mixed mode is similar to the mixed mode describedbelow in connection with FIG. 59 but bills are scanned as describedabove in connection with FIG. 52 and scanned patterns are correlatedagainst Canadian master patterns. Likewise German stranger and Germanmixed mode are similar to the stranger and mixed modes described belowin connection with FIG. 59 hut bills are scanned as described above inconnection with the scanning of German bills and scanned patterns arecorrelated against German master patterns.

FIG. 56 is a functional block diagram illustrating another embodiment ofa currency discriminator system 1662 according to the present invention.The discriminator system 1662 comprises an input receptacle 1664 forreceiving a stack of currency bills. A transport mechanism defining atransport path (as represented by arrows A and B) transports the billsin the input receptacle past one or more sensors of an authenticatingand discriminating unit 1666 to an output receptacle 1668 where thebills are re-stacked such that each bill is stacked on top of or behindthe previous bill so that the most recent bill is the top-most orrear-most bill. The authenticating and discriminating unit scans anddetermines the denomination of each passing bill. Any variety ofdiscriminating techniques may be used. For example, the discriminatingmethod disclosed in U.S. Pat. No. 5,295,196 (incorporated herein in itsentirety) may be employed to optically scan each bill. Depending on thecharacteristics of the discriminating unit employed, the discriminatormay be able to recognize bills only if fed face up or face down,regardless of whether fed face up or face down, only if fed in a forwardorientation or reverse orientation, regardless of whether fed in aforward or reverse orientation, or some combination thereof.Additionally, the discriminating unit may be able to scan only one sideor both sides of a bill. In addition to determining the denomination ofeach scanned bill, the authenticating and discriminating unit 1666 mayadditionally include various authenticating tests such as an ultravioletauthentication test as disclosed in U.S. patent application Ser. No.08/317,349 filed on Oct. 4, 1994 for a “Method and Apparatus forAuthenticating Documents Including Currency.”

Signals from the authenticating and discriminating unit 1666 are sent toa signal processor such as a central processor unit (“CPU”) 1670. TheCPU 1670 records of results of the authenticating and discriminatingtests in a memory 1672. When the authenticating and discriminating unit1666 is able to confirm the genuineness and denomination of a bill, thevalue of the bill is added to a total value counter in memory 1672 thatkeeps track of the total value of the stack of bills that were insertedin the input receptacle 1664 and scanned by the authenticating anddiscriminating unit 1666. Additionally, depending on the mode ofoperation of the discriminator system 1662, counters associated with oneor more denominations are maintained in the memory 1672. For example, a$1 counter may be maintained to record how many $1 bills were scanned bythe authenticating and discriminating unit 1666. Likewise, a $5 countermay be maintained to record how many $5 bills were scanned, and so on.In an operating mode where individual denomination counters aremaintained, the total value of the scanned bills may be determinedwithout maintaining a separate total value counter. The total value ofthe scanned bills and/or the number of each individual denomination maybe displayed on a display 1674 such as a monitor or LCD display.

As discussed above, a discriminating unit such as the authenticating anddiscriminating unit 1666 may not be able to identify the denomination ofone or more bills in the stack of bills loaded into the input receptacle1664. For example, if a bill is excessively worn or soiled or if thebill is torn a discriminating unit may not be able to identify the bill.Furthermore, some known discrimination methods do not have a highdiscrimination efficiency and thus are unable to identify bills whichvary even somewhat from an “ideal” bill condition or which are evensomewhat displaced by the transport mechanism relative to the scanningmechanism used to discriminate bills. Accordingly, such poorerperforming discriminating units may yield a relatively large number ofbills which are not identified. Alternatively, some discriminating unitsmay be capable of identifying bills only when they are fed in apredetermined manner. For example, some discriminators may require abill to be faced in a predetermined manner. Accordingly, when a bill isfed face down past a discriminating unit which can only identify billsfed face up, the discriminating unit can not identify the bill.Likewise, other discriminators require a specific edge of a bill to befed first, for example, the top edge of a bill. Accordingly, bills whichare not fed in the forward direction, that is, those that are fed in thereverse direction, are not identified by such a discriminating unit.

According to one embodiment, the discriminator system 1662 is designedso that when the authenticating and discriminating unit is unable toidentify a bill, the transport mechanism is stopped so that theunidentified bill is the last bill transported to the output receptacle.After the transport mechanism stops, the unidentified bill is then, forexample, positioned at the top of or at the rear of the stack of billsin the output receptacle 1668. The output receptacle 1668 is preferablypositioned within the discriminator system 1662 so that the operator mayconveniently see the flagged bill and/or remove it for closerinspection. Accordingly, the operator is able to easily see the billwhich has not been identified by the authenticating and discriminatingunit 1666. The operator may then either visually inspect the flaggedbill while it is resting on the top of or at the rear of the stack, oralternatively, the operator may chose to remove the bill from the outputreceptacle in order to examine the flagged bill more closely. Thediscriminator system 1662 may be designed to continue operationautomatically when a flagged bill is removed from the output receptacleor, according to one embodiment of the present invention, may bedesigned to require a selection element to be depressed. Uponexamination of a flagged bill by the operator, it may be found that theflagged bill is genuine even though it was not identified by thediscriminating unit. However, because the bill was not identified, thetotal value and/or denomination counters in the memory 1672 will notreflect its value. According to one embodiment, such an unidentifiedbill is removed from the output stack and either re-fed through thediscriminator or set aside. In the latter case, any genuine set asidebills are counted by hand.

In some discriminators, unidentified bills are routed to a separatereject receptacle. In prior such systems, an unidentified genuine billwould have to be removed from a reject receptacle and re-fed through thediscriminator or the stack of rejected bills would have to be counted byhand and the results separately recorded. Furthermore, because re-fedbills have gone unidentified once, they are more likely to gounidentified again and ultimately may have to be counted by hand.However, as discussed above, such procedures may increase the chance forhuman error or at least lower the efficiency of the discriminator andthe operator.

In order to avoid problems associated with re-feeding bills, countingbills by hand, and adding together separate totals, according to oneembodiment of the present invention a number of selection elementsassociated with individual denominations are provided. In FIG. 56, theseselection elements are in the form of keys or buttons of a keypad 1676or 62. Other types of selection elements such as switches or displayedkeys in a touch-screen environment may be employed. The operation of theselection elements will be described in more detail in connection withFIG. 59 but briefly when an operator determines that a flagged bill isacceptable, the operator may simply depress the selection elementassociated with the denomination of the flagged bill and thecorresponding denomination counter and/or the total value counter areappropriately incremented and the discriminator system 1662 or 10resumes operating again. As discussed above, a bill may be flagged forany number of reasons including the bill being a no call or suspectbill. In non-automatic restart discriminators, where an operator hasremoved a genuine flagged bill from the output receptacle for closerexamination, the bill is first replaced into the output receptaclebefore a corresponding selection element is chosen. An advantage of theabove described procedure is that appropriate counters are incrementedand the discriminator is restarted with the touch of a single key,greatly simplifying the operation of the discriminator system 1662 or 10while reducing the opportunities for human error. When an operatordetermines that a flagged bill is not acceptable, the operator mayremove the unacceptable flagged bill from the output receptacle withoutreplacement and depress a continuation key on the keypad 1676 or 62.When the continuation key is selected the denomination counters and thetotal value counter are not affected and the discriminator system 1662or 10 will resume operating again. In automatic restart discriminators,the removal of a bill from the output receptacle is treated as anindication that the bill is unacceptable and the discriminatorautomatically resumes operation without affecting the denominationcounters and/or total value counters.

Turning now to FIG. 57, there is shown a functional block diagramillustrating another embodiment of a document authenticator anddiscriminator according to the present invention. The discriminatorsystem 1680 comprises an input receptacle 1682 for receiving a stack ofcurrency bills. A transport mechanism defining a transport path (asrepresented by arrow C) transports the bills in the input receptacle,one at a time, past one or more sensors of an authenticating anddiscriminating unit 1684. Based on the results of the authenticating anddiscriminating unit 1684, a bill is either transported to one of aplurality of output receptacles 1686 (arrow D), to a reject receptacle1688 (arrow E), or to an operator inspection station 1690 (arrow F).When is bill is determined to be genuine and its denomination has beenidentified, the bill is transported to one of a plurality of outputreceptacles. For example, the discriminator system 1680 may compriseseven output receptacles 1686, one associated with each of seven U.S.denominations, i.e., $1, $2, $5, $10, $20, $50, and $100. The transportmechanism directs (arrow D) the identified bill to the correspondingoutput receptacle. Alternatively, where the authenticating anddiscriminating unit determines that a bill is a fake, the bill isimmediately routed (arrow E) to the reject receptacle 1688. Finally, ifa bill is not determined to be fake but for some reason theauthenticating and discriminating unit 1684 is not able to identify thedenomination of the bill, the flagged bill is routed (arrow F) to aninspection station and the discriminator system 1680 stops operating.The inspection station is preferably positioned within the discriminatorsystem 1680 so that the operator may conveniently see the flagged billand/or remove it for closer inspection. If the operator determines thatthe bill is acceptable, the operator returns the bill to the inspectionstation if it was removed and selects a selection element (not shown)corresponding to the denomination of the flagged bill. Appropriatecounters (not shown) are incremented, the discriminator system 1680resumes operation, and the flagged bill is routed (arrow G) to theoutput receptacle associated with the chosen selection element. On theother hand, if the operator determines that the flagged bill isunacceptable, the operator returns the bill to the inspection station ifit was removed and selects a continuation element (not shown). Thediscriminator system 1680 resumes operation, and the flagged bill isrouted (arrow H) to the reject receptacle 1688 without incrementing thecounters associated with the various denomination and/or the total valuecounters. Alternatively, the discriminator system 1680 may permit theoperator to place any unacceptable unidentified bills aside or into thereject receptacle by hand. While transport paths D and G and paths E andH are illustrated as separate paths, paths D and G and paths E and H,respectively, may be the same path so that all bills proceeding toeither one of the output receptacles 1686 or the reject receptacle 1688,respectively, are routed through the inspection station 1690.

Turning now to FIG. 58a, there is shown a functional block diagramillustrating another embodiment of a document authenticator anddiscriminator according to the present invention. The discriminatorsystem 1692 comprises an input receptacle 1694 for receiving a stack ofcurrency bills. A transport mechanism (as represented by arrow I)transports the bills in the input receptacle, one at a time, past one ormore sensors of an authenticating and discriminating unit 1696. Based onthe results of the authenticating and discriminating unit 1696, a billis either transported to a single output receptacle 1698 (arrow J) or toan operator inspection station 1699 (arrow K). When a bill is determinedto be genuine and its denomination has been identified, the bill istransported to the single output receptacle. Alternatively, where theauthenticating and discriminating unit determines that a bill is a fakeor for some reason the authenticating and discriminating unit 1696 isnot able to identify the denomination of the bill, the flagged bill isrouted (arrow K) to an inspection station and the discriminator system1692 stops operating. The inspection station is preferably positionedwithin the discriminator system 1692 so that the operator mayconveniently see the flagged bill and/or remove it for closerinspection. Where a bill has been positively determined to be a fake bythe authenticating and discriminating unit 1696, an appropriateindication, for example, via a message in a display or the illuminationof a light, can be given to the operator as to the lack of genuinenessof the bill. The operator may then remove the bill without replacementfrom the inspection station 1699 and select a continuation element.Where a bill has not been positively identified as a fake nor has hadits denomination identified and where the operator determines that thebill is acceptable, the operator returns the bill to the inspectionstation if it was removed and selects a selection element (not shown)corresponding to the denomination of the flagged bill. Appropriatecounters (not shown) are incremented, the discriminator system 1692resumes operation, and the flagged bill is routed (arrow L) to thesingle output receptacle 1698. On the other hand, if the operatordetermines that the flagged bill is unacceptable, the operator removesthe bill without replacement from the inspection station and selects acontinuation element (not shown). The discriminator system 1692 resumesoperation without incrementing the counters associated with the variousdenomination and/or the total value counters. While transport paths Jand L are illustrated as separate paths, they may be the same path sothat all bills proceeding to the single output receptacle 1698 arerouted through the inspection station 1699.

Turning now to FIG. 58b, there is shown a functional block diagramillustrating another embodiment of a document authenticator anddiscriminator according to the present invention. The discriminatorsystem 1693 comprises an input receptacle 1694′ for receiving a stack ofcurrency bills. A transport mechanism (as represented by arrow I′)transports the bills in the input receptacle, one at a time, past one ormore sensors of an authenticating and discriminating unit 1696′. Basedon the results of the authenticating and discriminating unit 1696′, abill is either transported to one of two output receptacles 1698′ (arrowJ′) or 1698″ (arrow J″) or to an operator inspection station 1699′(arrow K′). When a bill is determined to be genuine and its denominationhas been identified, the bill is transported to one of the two outputreceptacles. Alternatively, where the authenticating and discriminatingunit determines that a bill is a fake or for some reason theauthenticating and discriminating unit 1696′ is not able to identify thedenomination of the bill, the flagged bill is routed (arrow K′) to aninspection station and the discriminator system 1693 stops operating.The inspection station is preferably positioned within the discriminatorsystem 1693 so that the operator may conveniently see the flagged billand/or remove it for closer inspection. Where a bill has been positivelydetermined to be a fake by the authenticating and discriminating unit1696′, an appropriate indication, for example, via a message in adisplay or the illumination of a light, can be given to the operator asto the lack of genuineness of the bill. The operator may then remove thebill without replacement from the inspection station 1699′ and select acontinuation element. Where a bill has not been positively identified asa fake nor has had its denomination identified and where the operatordetermines that the bill is acceptable, the operator returns the bill tothe inspection station if it was removed and selects a selection element(not shown) corresponding to the denomination of the flagged bill.Appropriate counters (not shown) are incremented, the discriminatorsystem 1693 resumes operation, and the flagged bill is routed (arrow L′or arrow L″) to one of the two output receptacles 1698′ and 1698″. Onthe other hand, if the operator determines that the flagged bill isunacceptable, the operator removes the bill without replacement from theinspection station and selects a continuation element (not shown). Thediscriminator system 1693 resumes operation without incrementing thecounters associated with the various denomination and/or the total valuecounters. While transport paths J′, J″ and L′, L″ are illustrated asseparate paths, they may be the same path so that all bills proceedingto one of the two output receptacles 1698′, 1698″ are routed through theinspection station 1699′.

Turning now to FIG. 58c, there is shown a functional block diagramillustrating another embodiment of a document authenticator anddiscriminator according to the present invention. The discriminatorsystem 2202 comprises an input receptacle 2204 for receiving a stack ofcurrency bills. A transport mechanism defining a transport path (asrepresented by arrow M) transports the bills in the input receptacle,one at a time, past one or more sensors of an authenticating anddiscriminating unit 2206. Bills are then transported to one of aplurality of output receptacles 2208 (arrow N). In one embodiment, wherethe authenticating and discriminating unit determines that a bill is afake, the flagged bill is routed to a separate one of said outputreceptacles. The operation of the discriminator may or may not then besuspended. When a bill is not determined to be fake but for some reasonthe authenticating and discriminating unit 2206 is not able to identifythe denomination of the bill, the no call bill may be transported one ofthe output receptacles. In one embodiment, no call bills are transportedto a separate one of the output receptacles. In another embodiment, nocalls are not delivered to a special separate output receptacle. Theoperation of the discriminator may or may not then be suspended. Forexample, in a two output pocket discriminator, all bills may betransported to the same output receptacle regardless of whether they aredetermined to be suspect, no call, or properly identified. In thisexample, the operation of the discriminator may be suspended and anappropriate message displayed when a suspect or no call bill isencountered. Alternatively, suspect bills may be delivered to one of theoutput receptacles (i.e., a reject receptacle) and no calls andidentified bills may be sent to the other output receptacle. In thisexample, the operation of the discriminator need not be suspended when asuspect bill is encountered but may be suspended when a no call bill isencountered. If the operation is suspended at the time the no call billis detected and the operator determines that the no call bill isacceptable, the operator returns the bill to the output receptacle fromwhich it was removed (if it was removed) and selects a selection element(not shown) corresponding to the denomination of the flagged bill.Appropriate counters (not shown) are incremented, the discriminatorsystem 2202 resumes operation. On the other hand, if the operatordetermines that the flagged bill is unacceptable, the operator removesthe bill without replacement form the output receptacle and selects acontinuation element (not shown). The discriminator system 2202 resumesoperation without incrementing the counters associated with the variousdenomination and/or the total value counters. In another embodiment, nocall bills are delivered to an output receptacle separate from the oneor more output receptacles receiving identified bills. The operation ofthe discriminator need not be suspended until all the bills placed inthe input receptacle have been processed. The value of any no call billsmay then be added to the appropriate counters after the stack of billshas been processed through a reconciliation process. The entering of thevalue of no call bills is discussed in more detail below in connectionwith FIGS. 62-67.

Turning now to FIG. 58d, there is shown a functional block diagramillustrating another embodiment of a document authenticator anddiscriminator according to the present invention. The discriminatorsystem 2203 comprises an input receptacle 2204′ for receiving a stack ofcurrency bills. A transport mechanism defining a transport path (asrepresented by arrow M′) transports the bills in the input receptacle,one at a time, past one or more sensors of an authenticating anddiscriminating unit 2206′. Bills are then transported to one of twooutput receptacles 2208′, 2208″ (arrows N′, N″). In one embodiment,where the authenticating and discriminating unit determines that a billis a fake, the flagged bill is routed to a specific one of said outputreceptacles. The operation of the discriminator may or may not then besuspended. When a bill is not determined to be fake but for some reasonthe authenticating and discriminating unit 2206′ is not able to identifythe denomination of the bill, the no call bill may be transported to oneof the output receptacles. In one embodiment, no call bills aretransported to a specific one of the output receptacles. In anotherembodiment, no calls are not delivered to a special separate outputreceptacle. The operation of the discriminator may or may not then besuspended. For example, in a two output pocket discriminator, all billsmay be transported to the same output receptacle regardless of whetherthey are determined to be suspect, no call, or properly identified. Inthis example, the operation of the discriminator may be suspended and anappropriate message displayed when a suspect or no call bill isencountered. Alternatively, suspect bills may be delivered to a specificone of the two output receptacles (i.e., a reject receptacle) and nocalls and identified bills may be sent to the other output receptacle.In this example, the operation of the discriminator need not besuspended when a suspect bill is encountered but may be suspended when ano call bill is encountered. If the operation is suspended at the timethe no call bill is detected and the operator determines that the nocall bill is acceptable, the operator returns the bill to the outputreceptacle from which it was removed (if it was removed) and selects aselection element (not shown) corresponding to the denomination of theflagged bill. Appropriate counters (not shown) are incremented, thediscriminator system 2203 resumes operation. On the other hand, if theoperator determines that the flagged bill is unacceptable, the operatorremoves the bill without replacement from the output receptacle andselects a continuation element (not shown). The discriminator system2203 resumes operation without incrementing the counters associated withthe various denomination and/or the total value counters. In anotherembodiment, no call bills are delivered to a specific output receptacleseparate from the output receptacle receiving identified bills. Theoperation of the discriminator need not be suspended until all the billsplaced in the input receptacle have been processed. Alternatively, theoperation of the discriminator need not be suspended when a no call isencountered but may be suspended when a suspect bill is detected so thatthe operator may remove any suspect bills from the discriminator. Thevalue of any no call bills may then be added to the appropriate countersafter the stack of bills has been processed through a reconciliationprocess. The entering of the value of no call bills is discussed in moredetail below in connection with FIGS. 62-67.

The operation of the selection elements according to one embodiment willnow be described in more detail in conjunction with FIG. 59 which is afront view of a control panel 61 of one embodiment of the presentinvention. The control panel 61 comprises a keypad 62 and a displaysection 63. The keypad 62 comprises a plurality of keys including sevendenomination selection elements 64 a-64 g, each associated with one ofseven U.S. currency denominations, i.e., $1, $2, $5, $10, $20, $50, and$100. For foreign bill discriminators, the denomination selectionelements may be labeled according to the currency system which adiscriminator is designed to handle and accordingly, there may be moreor less than seven denomination selection elements. The $1 denominationselection key 64 a also serves as a mode selection key. The keypad 62also comprises a “Continuation” selection element 65. Variousinformation such as instructions, mode selection information,authentication and discrimination information, individual denominationcounter values, and total batch counter value are communicated to theoperator via an LCD 66 in the display section 63. A discriminatoraccording to one embodiment of the present invention has a number ofoperating modes including a mixed mode, a stranger mode, a sort mode, aface mode, and a forward/reverse orientation mode. The operation of adiscriminator having the denomination selection elements 64 a-64 g andthe continuation element 65 will now be discussed in connection withseveral operating modes.

(A) Mixed Mode

Mixed mode is designed to accept a stack of bills of mixed denomination,total the aggregate value of all the bills in the stack and display theaggregate value in the display 63. Information regarding the number ofbills of each individual denomination in a stack may also be stored indenomination counters. When an otherwise acceptable bill remainsunidentified after passing through the authenticating and discriminatingunit, operation of the discriminator may be resumed and thecorresponding denomination counter and/or the aggregate value countermay be appropriately incremented by selecting the denomination selectionkey 64 a-64 g associated with the denomination of the unidentified bill.For example, if the discriminator system 62 of FIG. 56 or 10 of FIG. 1stops operation with an otherwise acceptable $5 bill being the last billdeposited in the output receptacle, the operator may simply select key64 b. When key 64 b is depressed, the operation of the discriminator isresumed and the $5 denomination counter is incremented and/or theaggregate value counter is incremented by $5. Furthermore, in thediscriminator systems 1680 of FIG. 57 and 1692 of FIG. 58, the flaggedbill may be routed from the inspection station to an appropriate outputreceptacle. Otherwise, if the operator determines the flagged bill isunacceptable, the bill may be removed from the output receptacle ofFIGS. 1 or 56 or the inspection station of FIGS. 8 and 9 (or in thesystem 1680 of FIG. 57, the flagged bill may be routed to the rejectreceptacle 1688). The continuation key 65 is depressed after theunacceptable bill is removed, and the discriminator resumes operationwithout affecting the total value counter and/or the individualdenomination counters.

(B) Stranger Mode

Stranger mode is designed to accommodate a stack of bills all having thesame denomination, such as a stack of $10 bills. In such a mode, when astack of bills is processed by the discriminator the denomination of thefirst bill in the stack is determined and subsequent bills are flaggedif they are not of the same denomination. Alternatively, thediscriminator may be designed to permit the operator to designate thedenomination against which bills will be evaluated with those of adifferent denomination being flagged. Assuming the first bill in a stackdetermines the relevant denomination and assuming the first bill is a$10 bill, then provided all the bills in the stack are $10 bills, thedisplay 63 will indicate the aggregate value of the bills in the stackand/or the number of $10 bills in the stack. However, if a bill having adenomination other than $10 is included in the stack, the discriminatorwill stop operating with the non-$10 bill or “stranger bill” being thelast bill deposited in the output receptacle in the case of thediscriminator system 62 of FIG. 56 or 10 of FIG. 1 (or the inspectionstation of FIGS. 8 and 9). The stranger bill may then be removed fromthe output receptacle and the discriminator is started again eitherautomatically or by depression of the “Continuation” key 65 depending onthe set up of the discriminator system. An unidentified but otherwiseacceptable $10 bill may be handled in a manner similar to that describedabove in connection with the mixed mode, e.g., by depressing the $10denomination selection element 64 c, or alternatively, the unidentifiedbut otherwise acceptable $10 bill may be removed from the outputreceptacle and placed into the input hopper to be re-scanned. Upon thecompletion of processing the entire stack, the display 63 will indicatethe aggregate value of the $10 bills in the stack and/or the number of$10 bills in the stack. All bills having a denomination other than $10will have been set aside and will not be included in the totals.Alternatively, these stranger bills can be included in the totals viaoperator selection choices. For example, if a $5 stranger bill isdetected and flagged in a stack of $10 bills, the operator may beprompted via the display as to whether the $5 bill should beincorporated into the running totals. If the operator respondspositively, the $5 bill is incorporated into appropriate running totals,otherwise it is not. Alternatively, when the discriminator stops on astranger bill, such as a $5, the operator may depress the denominationselection element associated with that denomination to cause the valueof the stranger bill to be incorporated into the totals. Likewise forother types of flagged bills such as no calls. Alternatively, a set-upselection may be chosen whereby all stranger bills are automaticallyincorporated into appropriate running totals.

(C) Sort Mode

According to one embodiment, the sort mode is designed to accommodate astack of bills wherein the bills are separated by denomination. Forexample, all the $1 bills may be placed at the beginning of the stack,followed by all the $5 bills, followed by all the $10 bills, etc.Alternatively, the sort mode may be used in conjunction with a stack ofbills wherein the bills are mixed by denomination. The operation of thesort mode is similar to that of the stranger mode except that afterstopping upon the detection of a different denomination bill, thediscriminator is designed to resume operation upon removal of all billsfrom the output receptacle. Returning to the above example, assuming thefirst bill in a stack determines the relevant denomination and assumingthe first bill is a $1 bill, then the discriminator processes the billsin the stack until the first non-$1 bill is detected, which in thisexample is the first $5 bill. At that point, the discriminator will stopoperating with the first $5 being the last bill deposited in the outputreceptacle. The display 63 may be designed to indicate the aggregatevalue of the preceding $1 bills processed and/or the number of preceding$1 bills. The scanned $1 bills and the first $5 bill are removed fromthe output receptacle and placed in separate $1 and $5 bill stacks. Thediscriminator will start again automatically and subsequent bills willbe assessed relative to being $5 bills. The discriminator continuesprocessing bills until the first $10 bill is encountered. The aboveprocedure is repeated and the discriminator resumes operation untilencountering the first bill which is not a $10 bill, and so on. Upon thecompletion of processing the entire stack, the display 63 will indicatethe aggregate value of all the bills in the stack and/or the number ofbills of each denomination in the stack. This mode permits the operatorto separate a stack of bills having multiple denominations into separatestacks according to denomination.

(D) Face Mode

Face mode is designed to accommodate a stack of bills all faced in thesame direction, e.g., all placed in the input hopper face up (that isthe portrait or black side up for U.S. bills) and to detect any billsfacing the opposite direction. In such a mode, when a stack of bills isprocessed by the discriminator, the face orientation of the first billin the stack is determined and subsequent bills are flagged if they donot have the same face orientation. Alternatively, the discriminator maybe designed to permit designation of the face orientation to which billswill be evaluated with those having a different face orientation beingflagged. Assuming the first bill in a stack determines the relevant faceorientation and assuming the first bill is face up, then provided allthe bills in the stack are face up, the display 63 will indicate theaggregate value of the bills in the stack and/or the number of bills ofeach denomination in the stack. However. if a bill faced in the oppositedirection (i.e., face down in this example) is included in the stack,the discriminator will stop operating with the reverse-faced bill beingthe last bill deposited in the output receptacle. The reverse-faced billthen may be removed from the output receptacle. In automatic re-startembodiments, the removal of the reverse-faced bill causes thediscriminator to continue operating. The removed bill may then be placedinto the input receptacle with the proper face orientation.Alternatively, in non-automatic re-start embodiments, the reverse-facedbill may be either placed into the input receptacle with the proper faceorientation and the continuation key 65 depressed, or placed back intothe output receptacle with the proper face orientation. Depending on theset up of the discriminator when a bill is placed back into the outputreceptacle with the proper face orientation, the denomination selectionkey associated with the reverse-faced bill may be selected, whereby theassociated denomination counter and/or aggregate value counter areappropriately incremented and the discriminator resumes operation.Alternatively, in embodiments wherein the discriminator is capable ofdetermining denomination regardless of face orientation, thecontinuation key 65 or a third key may be depressed whereby thediscriminator resumes operation and the appropriate denomination counterand/or total value counter is incremented in accordance with thedenomination identified by the discriminating unit. In discriminatorsthat require a specific face orientation, any reverse-faced bills willbe unidentified bills. In discriminators that can accept a billregardless of face orientation, reverse-faced bills may be properlyidentified. The later type of discriminator may have a discriminatingunit with a scanhead on each side of the transport path. Examples ofsuch dual-sided discriminators are disclosed above (see e.g., FIGS. 2a,6 c, 20 a, 26, and 42. The ability to detect and correct forreverse-faced bills is important as the Federal Reserve requirescurrency it receives to be faced in the same direction.

In a multi-output receptacle discriminator, the face mode may be used toroute all bills facing upward to one output receptacle and all billsfacing downward to another output receptacle. In single-sideddiscriminators, reverse-faced bills may be routed to an inspectionstation such as 1690 of FIG. 57 for manual turnover by the operator andthe unidentified reverse-faced bills may then be passed by thediscriminator again. In dual-sided discriminators, identifiedreverse-faced bills may be routed directly to an appropriate outputreceptacle. For example, in dual-sided discriminators bills may besorted both by face orientation and by denomination, e.g., face up $1bills into pocket #1, face down $1 bills into pocket #2, face up $5bills into pocket #3, and so on or simply by denomination, regardless offace orientation, e.g., all $1 bills into pocket #1 regardless of faceorientation, all $2 bills into pocket #2, etc.

(E) Forward/Reverse Orientation Mode

Forward/Reverse Orientation mode (“Orientation” mode) is designed toaccommodate a stack of bills all oriented in a predetermined forward orreverse orientation direction. For example in a discriminator that feedsbills along their narrow dimension, the forward direction may be definedas the fed direction whereby the top edge of a bill is fed first andconversely for the reverse direction. In a discriminator that feedsbills along their long dimension, the forward direction may be definedas the fed direction whereby the left edge of a bill is fed first andconversely for the reverse direction. In such a mode, when a stack ofbills is processed by the discriminator, the forward/reverse orientationof the first bill in the stack is determined and subsequent bills areflagged if they do not have the same forward/reverse orientation.Alternatively, the discriminator may be designed to permit the operatorto designate the forward/reverse onentation against which bills will beevaluated with those having a different forward/reverse orientationbeing flagged. Assuming the first bill in a stack determines therelevant forward/reverse orientation and assuming the first bill is fedin the forward direction, then provided all the bills in the stack arealso fed in the forward direction, the display 63 will indicate theaggregate value of the bills in the stack and/or the number of bills ofeach denomination in the stack. However, if a bill having the oppositeforward/reverse orientation is included in the stack, the discriminatorwill stop operating with the opposite forward/reverse oriented billbeing the last bill deposited in the output receptacle. The oppositeforward/reverse oriented bill then may be removed from the outputreceptacle. In automatic re-start embodiments, the removal of theopposite forward/reverse oriented bill causes the discriminator tocontinue operating. The removed bill may then be placed into the inputreceptacle with the proper face orientation. Alternatively, innon-automatic re-start embodiments, the opposite forward/reverseoriented bill may be either placed into the input receptacle with theproper forward/reverse orientation and the continuation key 65depressed, or placed back into the output receptacle with the properforward/reverse orientation. Depending on the set up of thediscriminator when a bill is placed back into the output receptacle withthe proper forward/reverse orientation, the denomination selection keyassociated with the opposite forward/reverse oriented bill may beselected, whereby the associated denomination counter and/or aggregatevalue counter are appropriately incremented and the discriminatorresumes operation. Alternatively, in embodiments wherein thediscriminator is capable of determining denomination regardless offorward/reverse orientation, the continuation key 65 or a the third keymay be depressed whereby the discriminator resumes operation and theappropriate denomination counter and/or total value counter isincremented in accordance with the denomination identified by thediscriminating unit. In single-direction discriminators, anyreverse-oriented bills will be unidentified bills. In dual-directiondiscriminators, reverse-oriented bills may be properly identified by thediscriminating unit. An example of a dual-direction discriminatingsystem is described above connection with FIGS. 1-7b and in U.S. Pat.No. 5,295,196. The ability to detect and correct for reverse-orientedbills is important as the Federal Reserve may soon require currency itreceives to be oriented in the same forward/reverse direction.

In a multi-output receptacle discriminator, the orientation mode may beused to route all bills oriented in the forward direction to one outputreceptacle and all bills oriented in the reverse direction to anotheroutput receptacle. In single-direction discriminators, reverse-orientedbills may be routed to an inspection station such as 1690 of FIG. 57 formanual turnover by the operator and the unidentified reverse-orientedbills may then be passed by the discriminator again. In discriminatorscapable of identifying bills fed in both forward and reverse directions(“dual-direction discriminators”), identified reverse-oriented bills maybe routed directly to an appropriate output receptacle. For example, indual-direction discriminators bills may be sorted both byforward/reverse orientation and by denomination, e.g., forward $1 billsinto pocket #1, reverse $1 bills into pocket #2, forward $5 bills intopocket #3, and so on or simply by denomination, regardless offorward/reverse orientation, e.g., all $1 bills into pocket #1regardless of forward/reverse orientation, all $2 bills into pocket #2,etc.

Suspect Mode

In addition to the above modes, a suspect mode may be activated inconnection with these modes whereby one or more authentication tests maybe performed on the bills in a stack. When a bill fails anauthentication test, the discriminator will stop with the failing orsuspect bill being the last bill transported to the output receptacle.The suspect bill then may be removed from the output receptacle and setaside.

Likewise, one or more of the above described modes may be activated atthe same time. For example, the face mode and the forward/reverseorientation mode may be activated at the same time. In such a case,bills that are either reverse-faced or opposite forward/reverse orientedwill be flagged.

According to one embodiment, when a bill is flagged, for example, bystopping the transport motor with the flagged bill being the last billdeposited in the output receptacle, the discriminating device indicatesto the operator why the bill was flagged. This indication may beaccomplished by, for example, lighting an appropriate light, generatingan appropriate sound, and/or displaying an appropriate message in thedisplay section 63 (FIG. 59). Such indication might include, forexample, “no call”, “stranger”, “failed magnetic test”, “failed UVtest”, “no security thread”, etc.

Referring now to FIGS. 60a-60 c, there is shown a side view of oneembodiment of a document authenticating system according to the presentinvention, a top view of the embodiment of FIG. 60a along the direction60 b, and a top view of the embodiment of FIG. 60a along the direction60 c, respectively. An ultraviolet (“UV”) light source 2102 illuminatesa document 2104. Depending upon the characteristics of the document,ultraviolet light may be reflected off the document and/or fluorescentlight may be emitted from the document. A detection system 2106 ispositioned so as to receive any light reflected or emitted toward it butnot to receive any UV light directly from the light source 2102. Thedetection system 2106 comprises a UV sensor 2108, a fluorescence sensor2110, filters, and a plastic housing. The light source 2102 and thedetection system 2106 are both mounted to a printed circuit board 2112.The document 2104 is transported in the direction indicated by arrow Aby a transport system (not shown). The document is transported over atransport plate 2114 which has a rectangular opening 2116 in it topermit passage of light to and from the document. In one embodiment ofthe present invention, the rectangular opening 2116 is 1.375 inches(3.493 cm) by 0.375 inches (0.953 cm). To minimize dust accumulationonto the light source 2102 and the detection system 2106 and to preventdocument jams, the opening 2116 is covered with a transparent UVtransmitting acrylic window 2118. To further reduce dust accumulation,the UV light source 2102 and the detection system 2106 are completelyenclosed within a housing (not shown) comprising the transport plate2114.

Referring now to FIG. 61, there is shown a functional block diagramillustrating one embodiment of a document authenticating systemaccording to the present invention. FIG. 61 shows an UV sensor 2202, afluorescence sensor 2204, and filters 2206, 2208 of a detection systemsuch as the detection system 2106 of FIG. 60. Light from the documentpasses through the filters 2206, 2208 before striking the sensors 2202,2204, respectively. An ultraviolet filter 2206 filters out visible lightand permits UV light to be transmitted and hence to strike UV sensor2202. Similarly, a visible light filter 2208 filters out UV light andpermits visible light to be transmitted and hence to strike fluorescencesensor 2204. Accordingly, UV light, which has a wavelength below 400 nm,is prevented from striking the fluorescence sensor 2204 and visiblelight, which has a wavelength greater than 400 nm, is prevented fromstriking the UV sensor 2202. In one embodiment the UV filter 2206transmits light having a wavelength between about 260 nm and about 380nm and has a peak transmittance at 360 nm. In one embodiment, thevisible light filter 2208 is a blue filter and preferably transmitslight having a wavelength between about 415 nm and about 620 nm and hasa peak transmittance at 450 nm. The above preferred blue filtercomprises a combination of a blue component filter and a yellowcomponent filter. The blue component filter transmits light having awavelength between about 320 nm and about 620 nm and has a peaktransmittance at 450 nm. The yellow component filter transmits lighthaving a wavelength between about 415 nm and about 2800 nm. Examples ofsuitable filters are UG1 (UV filter), BG23 (blue bandpass filter), andGG420 (yellow longpass filter), all manufactured by Schott. In oneembodiment the filters are about 8 mm in diameter and about 1.5 mmthick.

The UV sensor 2202 outputs an analog signal proportional to the amountof light incident thereon and this signal is amplified by amplifier 2210and fed to a microcontroller 2212. Similarly, the fluorescence sensor2204 outputs an analog signal proportional to the amount of lightincident thereon and this signal is amplified by amplifier 2214 and fedto a microcontroller 2212. Analog-to-digital converters 2216 within themicrocontroller 2212 convert the signals from the amplifiers 2210, 2214to digital and these digital signals are processed by the software ofthe microcontroller 2212. The UV sensor 2202 may be, for example, anultraviolet enhanced photodiode sensitive to light having a wavelengthof about 360 nm and the fluorescence sensor 2204 may be a blue enhancedphotodiode sensitive to light having a wavelength of about 450 nm. Suchphotodiodes are available from, for example, Advanced Photonix, Inc.,Massachusetts. The microcontroller 2212 may be, for example, a Motorola68HC16.

The exact characteristics of the sensors 2202, 2204 and the filters2206, 2208 including the wavelength transmittance ranges of the abovefilters are not as critical to the present invention as the preventionof the fluorescence sensor from generating an output signal in responseto ultraviolet light and the ultraviolet sensor from generating anoutput signal in response to visible light. For example, instead of, orin addition to, filters, a authentication system according to thepresent invention may employ an ultraviolet sensor which is notresponsive to light having a wavelength longer than 400 nm and/or afluorescence sensor which is not responsive to light having a wavelengthshorter than 400 nm.

Calibration potentiometers 2218, 2220 permit the gains of amplifiers2210, 2214 to be adjusted to appropriate levels. Calibration may beperformed by positioning a piece of white fluorescent paper on thetransport plate 2114 so that it completely covers the rectangularopening 2116 of FIG. 60. The potentiometers 2218, 2220 may then beadjusted so that the output of the amplifiers 2210, 2214 is 5 volts.

The implementation of one embodiment of a document authenticating systemaccording to the present invention as illustrated in FIG. 61 withrespect to the authentication of U.S. currency will now be described. Asdiscussed above, it has been determined that genuine United Statescurrency reflects a high level of ultraviolet light and does notfluoresce under ultraviolet illumination. It has also been determinedthat under ultraviolet illumination counterfeit United States currencyexhibits one of the four sets of characteristics listed below:

1) Reflects a low level of ultraviolet light and fluoresces;

2) Reflects a low level of ultraviolet light and does not fluoresce;

3) Reflects a high level of ultraviolet light and fluoresces;

4) Reflects a high level of ultraviolet light and does not fluoresce.Counterfeit bills in categories (1) and (2) may be detected by acurrency authenticator employing an ultraviolet light reflection testaccording to one embodiment of the present invention. Counterfeit billsin category (3) may be detected by a currency authenticator employingboth an ultraviolet reflection test and a fluorescence test according toanother embodiment of the present invention. Only counterfeits incategory (4) are not detected by the authenticating methods of thepresent invention.

According to one embodiment of the present invention, fluorescence isdetermined by any signal that is above the noise floor. Thus, theamplified fluorescent sensor signal 2222 will be approximately 0 voltsfor genuine U.S. currency and will vary between approximately 0 and 5volts for counterfeit bills depending upon their fluorescentcharacteristics. Accordingly, an authenticating system according to oneembodiment of the present invention will reject bills when signal 2222exceeds approximately 0 volts.

According to one embodiment of the present invention, a high level ofreflected UV light (“high UV”) is indicated when the amplified UV sensorsignal 2224 is above a predetermined threshold. The high/low UVthreshold is a function of lamp intensity and reflectance. Lampintensity can degrade by as much as 50% over the life of the lamp andcan be further attenuated by dust accumulation on the lamp and thesensors. The problem of dust accumulation is mitigated by enclosing thelamp and sensors in a housing as discussed above. An authenticatingsystem according to one embodiment of the present invention tracks theintensity of the UV light source and readjusts the high/low thresholdaccordingly. The degradation of the UV light source may be compensatedfor by periodically feeding a genuine bill into the system, sampling theoutput of the UV sensor, and adjusting the threshold accordingly.Alternatively, degradation may be compensated for by periodicallysampling the output of the UV sensor when no bill is present in therectangular opening 2116 of the transport plate 2114. It is noted that acertain amount of UV light is always reflected off the acrylic window2118. By periodically sampling the output of the UV sensor when no billis present, the system can compensate for light source degradation.Furthermore, such sampling could also be used to indicate to theoperator of the system when the ultraviolet light source has burned outor otherwise requires replacement. This may be accomplished, forexample, by means of a display reading or an illuminated light emittingdiode (“LED”). The amplified ultraviolet sensor signal 2224 willinitially vary between 1.0 and 5.0 volts depending upon the UVreflectance characteristics of the document being scanned and willslowly drift downward as the light source degrades. In an alternativeembodiment to one embodiment wherein the threshold level is adjusted asthe light source degrades, the sampling of the UV sensor output may beused to adjust the gain of the amplifier 2210 thereby maintaining theoutput of the amplifier 2210 at its initial levels.

It has been found that the voltage ratio between counterfeit and genuineU.S. bills varies from a discernable 2-to-1 ratio to a non-discernableratio. According to one embodiment of the present invention a 2-to-1ratio is used to discriminate between genuine and counterfeit bills. Forexample, if a genuine U.S. bill generates an amplified UV output sensorsignal 2224 of 4.0 volts, documents generating an amplified UV outputsensor signal 2224 of 2.0 volts or less will be rejected as counterfeit.As described above, this threshold of 2.0 volts may either be lowered asthe light source degrades or the gain of the amplifier 2210 may beadjusted so that 2.0 volts remains an appropriate threshold value.

According to one embodiment of the present invention, the determinationof whether the level of UV reflected off a document is high or low ismade by sampling the output of the UV sensor at a number of intervals,averaging the readings, and comparing the average level with thepredetermined high/low threshold. Alternatively, a comparison may bemade by measuring the amount of UV light reflected at a number oflocations on the bill and comparing these measurements with thoseobtained from genuine bills. Alternatively, the output of one or more UVsensors may be processed to generate one or more patterns of reflectedUV light and these patterns may be compared to the patterns generated bygenuine bills. Such a pattern generation and comparison technique may beperformed by modifying an optical pattern technique such as thatdisclosed in U.S. Pat. No. 5,295,196 incorporated herein by reference inits entirety or in U.S. patent application Ser. No. 08/287,882 filedAug. 9, 1994 for a “Method and Apparatus for Document Identification,”incorporated herein by reference in its entirety.

In a similar manner, the presence of fluorescence may be performed bysampling the output of the fluorescence sensor at a number of intervals.However, in one embodiment, a bill is rejected as counterfeit U.S.currency if any of the sampled outputs rise above the noise floor.However, the alternative methods discussed above with respect toprocessing the signal or signals of a UV sensor or sensors may also beemployed, especially with respect to currencies of other countries orother types of documents which may employ as security features certainlocations or patterns of fluorescent materials.

A currency authenticating system according to the present invention maybe provided with means, such as a display, to indicate to the operatorthe reasons why a document has been rejected, e.g., messages such as “UVFAILURE” or “FLUORESCENCE FAILURE.” A currency authenticating systemaccording to the present invention may also permit the operator toselectively choose to activate or deactivate either the UV reflectiontest or the fluorescence test or both. A currency authenticating systemaccording to the present invention may also be provided with means foradjusting the sensitivities of the UV reflection and/or fluorescencetest, for example, by adjusting the respective thresholds. For example,in the case of U.S. currency, a system according to the presentinvention may permit the high/low threshold to be adjusted, for example,either in absolute voltage terms or in genuine/suspect ratio terms.

Means for entering the value of no call bills were discussed above inconnection with FIG. 59 and the operating modes discussed above. Nowseveral additional means will be discussed in connection with FIGS.62-66. FIG. 62 is a front view of a control panel 2302 similar to thatof FIG. 59. The control panel 2302 comprises a display area 2304,several denomination selection elements 2306 a-g in the form of keys,left and right scroll keys 2308 a-b, an accept selection element 2310,and a continuation selection element 2312. Each denomination selectionelement 2306 a-g has a prompting means associated therewith. In FIG. 62,the prompting means are in the form of small lights or lamps 2314 a-gsuch as LEDs. In FIG. 62, the light 2314 d associated with the $10denomination key 2306 d is illuminated so as to prompt the operator thata denomination of $10 is being suggested. Alternatively, instead of thelamps 2314 a-g being separate from the denomination keys 2306 a-g, thedenomination keys could be in the form of illuminable keys whereby oneof the keys 2306 a-g would light up to suggest its correspondingdenomination to the operator. In place of, or in addition to, theilluminable lights 2314 a-g or keys, the display area 2304 may contain amessage to prompt or suggest a denomination to the operator. In FIG. 62,the display area 2304 contains the message “$10?” to suggest thedenomination of $10. In the embodiment of FIG. 59, the display area 63may be used to suggest a denomination to the operator without the needof illuminable lights and keys.

The control panel 2402 of FIG. 63 is similar to the control panel 2302of FIG. 62; however, the denomination selection elements 2406 a-g,scroll keys 2408 a-b, accept key 2410, and continuation key 2412 aredisplayed keys in a touch-screen environment. To select any given key,the operator touches the screen in the area of the key to be selected.The operation of a touch screen is described in more detail inconnection with FIG. 68. The discriminator may contain prompting meansto suggest a denomination to the operator. For example, an appropriatemessage may be displayed in a display area 2404. Alternatively, oradditionally, the prompting means may include means for highlighting oneof the denomination selection elements 2406 a-g. For example, theappearance of one of the denomination selection elements may be alteredsuch as by making it lighter or darker than the remaining denominationselection elements or reversing the video display (e.g., making lightportions dark and making the dark portions light or swapping thebackground and foreground colors). Alternatively, a designateddenomination selection element may be highlighted by surrounding it witha box, such as box 2414 surrounding the $10 key 2406 d.

Another embodiment of a control panel 2502 is depicted in FIG. 64. Thecontrol panel 2502 has several denomination indicating elements 2506 a-gin the form of menu list 2505, scroll keys 2508 a-b, an accept selectionelement 2510, and a continuation selection element 2512. The variousselection elements may be, for example, physical keys or displayed keysin a touch screen environment. For example, the menu list 2505 may bedisplayed in a non-touch screen activated display area while the scrollkeys 2508 a-b, accept key 2510, and continuation key 2512 may bephysical keys or displayed touch screen keys. In such an environment auser may accept a denominational selection by pressing the accept key2510 when the desired denomination indicating element is highlighted andmay use the scroll keys 2508 a-b to vary the denomination indicatingelement that is highlighted. Alternatively, the denomination indicatingelements 2506 a-g may themselves be selection elements such as by beingdisplayed touch screen active keys. In such an embodiment a givendenomination element may be made to be highlighted and/or selected bytouching the screen in the area of one of the denomination selectionelements 2506 a-g. The touching of the screen in the area of one of thedenomination selection elements may simply cause the associateddenomination selection element to become highlighted requiring thetouching and/or pressing of the accept key 2510 or alternatively mayconstitute acceptance of the associated denomination selection elementwithout requiring the separate selection of the accept key 2510. Thediscriminator may contain prompting means to suggest a denomination tothe operator. For example, an appropriate message may be displayed in adisplay area 2504. Alternatively, or additionally, the prompting meansmay include means for highlighting one of the denomination indicatingelements 2506 a-g. For example, the appearance of one of thedenomination indicating elements may be altered such as by making itlighter or darker than the remaining denomination indicating elements orby reversing the video display (e.g., making light portions dark andmaking the dark portions light or swapping the background and foregroundcolors). In FIG. 64, the hash marks are used to symbolize thealternating of the display of the $10 denomination indicating element2506 d relative to the other denomination indicating elements such as byusing a reverse video display.

Control panel 2602 of FIG. 65 is similar to control panel 2502 of FIG.64; however, the control panel 2602 does not have a separate displayarea. Additionally, the order of the denomination indicating elements2606 a-g of menu list 2605 is varied relative to those of menu list2505. The order of the denomination selection element may beuser-defined (i.e., the operator may preset the order in which thedenominations should be listed) or may be determined by thediscriminator and be, for example, based on the historical occurrence ofno calls of each denomination, based on the denomination of the mostrecently detected no call, based on calculated correlation values for agiven no call bill, or perhaps based on random selection. Such criteriawill be described in more detail below.

The control panel 2702 of FIGS. 66a and 66 b comprises a display area2704, an accept key 2710, a next or other denomination key 2711, and acontinuation key 2712. Alternatively, the accept key may be designated a“YES” key while the other denomination key may be designated a “NO” key.These keys may be physical keys or displayed keys. The discriminatorprompts or suggest a denomination by displaying an appropriate messagein the display area 2704. If the operator wishes to accept thisdenomination suggestion, the accept key 2710 may be selected. If otherthe operator wishes to select a different denomination, the otherdenomination key 2711 may be selected. If in the example given in FIG.66a the operator wishes to select a denomination other than the $5prompted in the display area 2704, the other denomination key 2711 maybe selected which results in prompting of a different denomination,e.g., $2 as shown in FIG. 66b. The “OTHER DENOM” key 2711 may berepeatedly selected to scroll through the different denominations.

The control panel 2802 of FIG. 67 is similar to that of FIGS. 66a-b andadditionally comprises scroll keys 2808 a-b. These scroll keys 2808 a-bmay be provided in addition to or in place of the other denomination key2811. The order in which denominations are suggested to an operator, forexample, in FIGS. 66 and 67, may be based on a variety of criteria aswill be discussed below such as user-defined criteria or order,historical information, previous bill denomination, correlation values,or previous no call information.

Now several embodiments of the operation of discriminators embodyingcontrol panels such as those of FIGS. 59 and 62-67 will be discussed.These can be employed in conjunction with a variety of discriminatorsand scanners such as those illustrated in FIGS. 1 and 56-58. Inparticular, several methods for reconciling the value of no call billswill be discussed in connection with these control panels. As discussedabove, for example, in connection with the several previously describedoperating modes, when a discriminator encounters a no call bill, thatis, when a discriminator is unable to determine or call the denominationof a bill, any counters keeping track of the number or value of eachdenomination of bills or of the total value of the bills processed willnot include the no call bill. Traditionally, any no calls bills had tobe set aside and manually counted by hand with the operator beingrequired to add their values to the totals provided by thediscriminator. As discussed above, this can lead to errors and reducedefficiency. To counter this problem, according to an embodiment of thepresent invention, means are provided for incorporating the value of nocall bills. In single pocket discriminators, reconciliation may beaccomplished on-the-fly with the discriminator suspending operation wheneach no call is encountered, prompting the operator to enter the valueof the no call, and then resuming operation. In multi-output pocketdiscriminators, no call bills may be reconciled either on-the-fly orafter the completion of processing all the bills placed in the inputhopper or after completion of processing some other designated batch ofbills. Under the first approach, the operation of the discriminator issuspended when each no call bill is detected with or without the no callbill being routed to a special location. The operator is then promptedto enter the value of the no call where upon the discriminator resumesoperation. Based on the value indicated by the operator, appropriatecounters are augmented. Under the second approach, any no call bills arerouted to a special location while the discriminator continuesprocessing subsequent bills. When all the bills have been processed, theoperator is prompted to reconcile the values of any intervening no callbills. For example, assume a stack of fifty bills is placed in the inputhopper and processed with four no calls being routed to a separateoutput receptacle from the receptacle or receptacles into which thebills whose denominations have been determined. After all fifty billshave been processed, the operation of the transport mechanism is haltedand the operator is prompted to reconcile the value of the four no callbills. The methods for reconciling these four no calls will be discussedbelow after describing several denomination indicating and/or promptingmeans and methods. Alternatively, instead of waiting until all the billsin the stack have been processed, the discriminator may prompt theoperator to reconcile the value of any no call bills while the remainingbills are still being processed. When the operator indicates thedenominations of the no call bills, appropriate counters are augmentedto reflect the value of the no call bills.

Several embodiments of means for permitting the operator to indicate thevalue of a flagged bill such as a no call and/or for prompting theoperator as to the value of a flagged bill such as a no call will no wbe discussed. A first method was discussed above in connection withseveral operating modes and in connection with FIG. 59. According to oneembodiment, the control panel of FIG. 59 comprises denominationindicating means in the form of the denomination selection elements 64a-g for permitting the operator to indicate the denomination of a billbut does not additionally comprise means for prompting the operator asto the denomination of a particular bill. Under this method, theoperator examines a no call bill. If the bill is acceptable, theoperator selects the denomination selection element associated with thedenomination of the no call bill and the appropriate counters areaugmented to reflect the value of the no call bill. For example, if theoperator determines a no call bill is an acceptable $10 bill, theoperator may press the $10 selection element 64 c of FIG. 59. If theoperation of the discriminator had been suspended, the selection of adenomination selection causes the operation of the discriminator toresume. In a on-the-fly reconciliating machine (i.e., one that suspendsoperation upon detection of each no call bill), if the operatordetermines that a particular no call bill is unacceptable, acontinuation selection element may be selected to cause thediscriminator to resume operation without negatively affecting thestatus of any counters. Under this approach, the denomination selectionelements provide the operator with means for indicating the value of ano call bill. In FIGS. 62-67, additional examples of means forindicating the value of no call bills are provided. For example, inFIGS. 62-65, according to one embodiment, a denomination may beindicated in a similar manner by pressing one of the denominationselection elements. Alternatively, or additionally, a denomination maybe indicated by selecting one of the denomination selection elements andselecting an accept key. Another example of a method of indicating aparticular denomination selection element would be by utilizing one ormore scroll keys. The selection of a denomination selection element maybe indicated by, for example, the lights 2314 of FIG. 62, or byhighlighting a particular selection element as in FIGS. 63-65.Alternatively a displayed message, as in FIGS. 62-64, 66, and 67, may beused to indicate which denomination is currently selected. The scrollkeys could be used to alter which denomination is presently selected,for example, by altering which light 2314 is illuminated, whichselection element is highlighted, or which denomination appears in thedisplayed message. Selection of an accept key while a particulardenomination is selected may be used to indicate the selecteddenomination to the discriminator.

In addition to means for permitting the operator to indicate thedenomination of one or more no calls, a discriminator may be providedwith one or more means of prompting the operator as to the denominationof a no call bill. These means can be the means used to indicate whichdenomination is currently selected, e.g., the lights 2314 of FIG. 62,the highlighting of FIGS. 63-65, and/or the displayed message of FIGS.62-64, 66, and 67. Several methods that may be employed in prompting theoperator to enter the value of one or more no call bills will now bediscussed.

A discriminator containing means for prompting an operator as to thevalue of a no call bill may base its selection of the denomination to beprompted to the operator on a variety of criteria. According to oneembodiment, default denomination or sequence of denominations may beemployed to prompt a denomination to an operator. For example, thediscriminator may begin by prompting the lowest denomination, e.g., $1.Alternatively, the discriminator may begin by prompting the operatorwith the first denomination in a pre-defined sequence or on a menu list.The order of the denominations in the sequence or on the menu list maybe a default order, e.g., increasing or decreasing denominational order,user-defined order, manufacturer-defined order.

According to another embodiment, a denomination to be prompted to theoperator is determined on a random basis. The discriminator simplyrandomly or pseudo-randomly chooses one of a plurality of denominationsand suggests this denomination to the operator. The denominationprompted to an operator may remain the same for all no call bills oralternatively, a new randomly selected denomination may be chosen foreach no call encountered. If the operator agrees that a given no callbill is of the denomination suggested by the prompting means and findsthe particular no call bill to be acceptable, the operator may simplychoose the accept element or the corresponding denomination selectionelement depending on the embodiment of the control panel employed. Ifthe operator finds a particular bill to be acceptable but does not havethe suggested denomination, the operator may alter the denomination thatis selected by, for example, altering the displayed suggesteddenomination by using the scroll keys, scrolling among the plurality ofdenomination selection and/or indicating elements, or directly selectingthe appropriate denomination by pressing or touching the appropriatedenomination selection element. If the operator finds that a no callbill is not acceptable, the operator may simply select a continuationkey.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of the denomination of the last billthat was identified by the discriminator. For example, suppose the tenthbill in a stack was determined by the discriminator to be a $10, theeleventh bill was a no call and indicated by the operator to be a $5bill, and the twelfth was a no call bill. According to this embodiment,the discriminator would suggest to the operator that the twelfth bill isa $10 bill. The operator may accept this suggestion or alter thesuggested denomination as described above.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of the denomination of the last nocall bill as indicated by the operator. For example, suppose the tenthbill was a no call and indicated by the operator to be a $5 bill, theeleventh bill in a stack was determined by the discriminator to be a$10, and the twelfth was a no call bill. According to this embodiment,the discriminator would suggest to the operator that the twelfth bill isa $5 bill. The operator may accept this suggestion or alter thesuggested denomination as described above.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of the denomination of theimmediately preceding bill, regardless of whether the denomination ofthat bill was determined by the discriminator or was indicated by theoperator. For example, suppose the tenth bill in a stack was determinedby the discriminator to be a $10, the eleventh bill was a no call andindicated by the operator to be a $5 bill, and the twelfth was also a nocall bill. According to this embodiment, the discriminator would suggestto the operator that the twelfth bill is a $5 bill. The operator mayaccept this suggestion or alter the suggested denomination as describedabove.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of historical information concerningno call bills such as statistical information regarding previous no callbills. For example, suppose that for a given discriminator 180 no callshad been encountered since the discriminator was placed in service.According to this embodiment, information regarding these no calls isstored in memory. Assume that of these 180 no call bills, 100 wereindicated by the operator to be $5s, 50 were $10s, and the remaining 30were $20s. According to this embodiment, the discriminator would suggestto the operator that a no call bill was a $5. The operator may acceptthis suggestion or alter the suggested denomination as described above.Variations on the data which constitute the historical basis may bemade. For example, the historical basis according to this embodiment maybe all no calls encountered since a given machine was place in serviceas in the above example, the last predetermined number of no callsdetected, e.g., the last 100 no calls detected, or the lastpredetermined number of bills processed, e.g., the no calls encounteredin the last 1000 bills processed. Alternatively, the historical basismay be set by the manufacturer based on historical data retrieved from anumber of discriminators.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of a comparison of informationretrieved from a given no call bill and master information associatedwith genuine bills. For example, in some discriminators, thedenomination of a bill is determined by scanning the bill, generating ascanned pattern from information retrieved via the scanning step, andcomparing the scanned pattern with one or more master patternsassociated with one or more genuine bills associated with one or moredenominations. If the scanned pattern sufficiently matches one of themaster patterns, the denomination of the bill is called or determined tobe the denomination associated with the best matching master pattern.However, in some discriminators, a scanned pattern must meet somethreshold degree of matching or correlation before the denomination of abill will be called. In such discriminators, bills whose scanned patterndoes not sufficiently match one of the master patterns are not called,i.e., they are no calls. According to the present embodiment, thediscriminator would suggest to the operator that a no call had thedenomination associated with the master pattern that most closelymatched its scanned pattern even though that match was insufficient tocall the denomination of the bill without the concurrence of theoperator. The operator may accept this suggestion or alter the suggesteddenomination as described above. For example, in a discriminator similarto that described in U.S. Pat. No. 5,295,196, the discriminator mayprompt the operator with the denomination associated with the masterpattern that has the highest correlation with the scanned patternassociated with the given no call bill. Additional examples may be madewith reference to FIGS. 13 and 19a-c. For example, with respect to FIG.13, if the highest correlation for a bill is below 800, the bill is a nocall bill. In such a case, assume the highest correlation is 790 andthis correlation is associated with a $1 bill. When this no call bill isto be reconciled, the discriminator would suggest to the operator thatthe no call was a $1 bill.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of preset criteria established bythe manufacturer. For example, in FIG. 64, the denomination indicatingelements are arranged in increasing denominational order. Thediscriminator may be designed to default so that a given one of thesedenomination selection elements is initially highlighted when no callbills are to be reconciled. For example, for each no call the $10element 2506 d may initially be selected. Alternatively, thediscriminator may be designed to default to the first denominationselection element listed, e.g., the $1 denomination element 2506 a.

According to another embodiment, a denomination to be prompted to theoperator is determined on the basis of user-defined criteria set by theoperator of a discriminator. For example, in FIG. 64, the operator maydesignate the discriminator to default so that a given one of thedenomination indicating elements is initially highlighted when no callbills are to be reconciled. For example, for each no call the operatormay designate that the $10 element 2506 d is to be initially selected.The operator may be permitted to set the default no call denomination,for example, in a set up mode entered into before bills in a stack areprocessed.

In addition to the ways discussed above whereby an initial denominationis prompted to the operator in connection with the reconciling a no callbill, according to other embodiments one or more alternate denominationsare may also be suggested. For example, according to the method wherebythe initial bill is suggested to the operator based on the denominationassociated with a master pattern having the highest correlation relativeto a scanned pattern, if the operator rejects the initial suggestion,the discriminator may be designed to then suggest an alternatedenomination based on the master pattern associated with a genuine billof a different denomination having the next highest correlation value.If the operator rejects the second suggestion, the discriminator may bedesigned to then suggest a second alternate denomination based on themaster pattern associated with a genuine bill of a differentdenomination having the next highest correlation value, and so on.

For example, suppose the highest correlation was associated with a $1,the second highest correlation was associated with $10, and the thirdhighest correlation was associated with $50. According to thisembodiment, the discriminator would initially suggest that the no callwas a $1. If the operator determined the no call was not a $1, thediscriminator would then suggest that the no call was a $10. If theoperator determined the no call was not a $10, the discriminator wouldthen suggest that the no call was a $50. For example, according to theembodiment of FIGS. 66a-b, the discriminator would first ask whether theno call was a $1 by displaying the message “$1?” in the display area2704. If the no call was a $1, the operator would depress the accept oryes key 2710. If the no call was not a $1 bill, the operator woulddepress the other denomination or no key 2711, in which case, thedisplay area would display the message “$10?” and so on. Alternatively,the denomination selection elements may be arranged so that theirrelative order is based on the correlation results. For example, takingthe menu list 2605 of FIG. 65, the denomination elements may be orderedin the order of decreasing correlation values, e.g., according to theprevious example with the $1 denomination element being listed first,the $10 denomination element being listed second, the $50 denominationelement being listed third and so on. Alternatively, the denominationelements may be listed in the reverse order. According to anotherembodiment, the denomination element associated with the highestcorrelation may be listed in the middle of the list surrounded by thedenomination elements associated with the second and third highestcorrelations, and so on. For the above example, the $1 element 2606 awould be listed in the middle of the menu list 2605 surrounded by the$10 element 2606 d on one side and the $50 element 2606 f on the otherside.

Likewise the order in which denominations are suggested to the operatorand/or arranged on the control panel may be based on other criteria suchas those described above, such as the prior bill information (e.g., lastbill, last no call, last call denomination), historical information,user-defined order, manufacturer-defined order, and random order. Forexample, using the historical data example given above based on 180 nocalls (100 $5 no calls, 50 $10 no calls, and 30 $20 no calls), the orderthat denominations are suggested to the operator may be first $5, then$10, and then $20. Alternatively, using the last bill information andassuming the following sequence of bills ($2, $5, $5, $5, $20, $10, nocall indicated to be a $50, no call); the discriminator would suggestdenominations for the last no call in the following order: $50, $10,$20, $5, $2. Likewise the order in which the denominations are arrangedon a control panel such as in FIGS. 65 and 63 may be determined based onsuch information, for example, according to the orders described abovein connection with using correlation values. For example, thedenominations may be listed in the prompting order suggested above(e.g., $5, $10, $20 in the historical information example and $50, $10,$20, $5, $2 in the last bill example). Alternatively they may be listedin the reverse order. Alternatively, they may be arranged with the firstsuggested denomination being in the center of the list and beinginitially highlighted or selected. This first suggested denomination maybe surrounded by the second and third suggested denominations which arein turn surrounded by the fourth and fifth suggested denomination, andso on. A default sequence may be used to provide the order for anyremaining denominations which are not dictated by a particular promptingcriteria in a given situation. In the above examples, the denominationsmight be arranged on a menu list in the following orders: $2, $1, $10,$5, $20, $50, $100 for the historical information example and $1, $5,$10, $50, $20, $2, $100. In general, an example of a listing orderaccording to this approach could be from top to bottom: 6th priority orsuggested denomination, 4th, 2nd, 1st, 3rd, 5th, and 7th.

Embodiments arranging the respective order in which denominations aresuggested to the operator and/or displayed on the control panel willlikely aid the operator by reducing the projected number of times theoperator will need to hit one of the scroll keys and/or “OTHER DENOM” or“NO” key.

Now several methods will be described in connection reconciliation of nocalls in multi-output pocket machines after all bills in a stack havebeen processed. Recalling a previous example in which four no call billswere separated out from a stack of fifty bills and the machine haltedafter processing all fifty bills, the discriminator then prompts theoperator to reconcile the value of the four no call bills. For example,assume the no call bills corresponded to the 5th, 20th, 30th, and 31stbills in the stack and were $2, $50, $10, and $2 bills respectively. Thedegree of intelligence employed by the discriminator in prompting theoperator to reconcile the value of the no call bills may vary dependingon the particular embodiment employed. According to one embodiment theoperator may depress or select the denomination selection elementscorresponding the denominations of the no call bills without anyprompting from the discriminator as to their respective denominations.For example, using the control panel of FIG. 59, the operator woulddepress the $2 selection element 64 g twice, the $10 selection element64 c once, and the $50 selection element 64 e once. The discriminatormay or may not inform the operator that four no call bills must bereconciled and may or may not limit the operator to entering fourdenominations. Likewise, in other embodiments, the operator may use thescroll keys to cause the desired denomination to become selected andthen depress the accept key. Alternatively, a numerical keypad may beprovided for permitting the operator to indicate the number of bills ofeach denomination that have not been called. For example, the aboveexample, the operator could use the scroll keys so that the $2denomination was selected, then press “2” on the keypad for the numberof $2 no calls in the batch, and then press an enter or accept key. Thenthe operator could use the scroll keys so that the $10 denomination wasselected, then press “1” on the keypad for the number of $10 no calls inthe batch, and then press an enter or accept key and so on. The keypadmay comprise, for example, keys or selection elements associated withthe digits 0-9.

Alternatively, the discriminator may prompt the operator as to thedenomination of each no call bill, for example, by employing one of theprompting methods discussed above, e.g., default, random, user-definedcriteria, manufacturer defined criteria, prior bill information (lastbill, last no call, last called denomination), historical information,scanned and master comparison information (e.g., highest correlation).For example, the discriminator may serially interrogate the examiner asto the denomination of each no call, for example, the display mayinitially query “Is 1st no call a $2?”. Depending on the embodiment ofthe control panel being used, the operator could then select “ACCEPT” or“YES” or select the $2 denomination selection element, select “OTHERDENOM” or “NO” or use the scroll keys or select the appropriatedenomination selection element, or if the operator finds the first billunacceptable, the operator may put the first no call bill aside andselect “CONT”. The discriminator may then query the operator as to thedenomination of the second no call bill, and so on. The denominationprompted to the operator would depend on the prompting criteriaemployed. For example, suppose the prompting criteria was thedenomination of the preceding bill and further suppose that in the fourno call example given above that the first bill was a $2, the 2nd billwas a $10, the 3rd bill was a $1, the 4th bill was a $1, the 19th billwas a $50, the 29th bill was a $10, and as stated above, the 30th billwas a $10. The discriminator would then prompt the operator as towhether the first no call was a $1. Since the first no call is a $2, theoperator would choose “NO”, “OTHER DENOM”, scroll, or hit the $2selection element depending on the embodiment be used. If the “NO” or“OTHER DENOM” key were pressed, the discriminator would review thepreceding bills in reverse order and suggest the first denominationencountered that had not already been suggested, in this case a $10. Ifthe “NO” or “OTHER DENOM” key were pressed again, the discriminatorwould then suggest a $2. A predetermined default sequence may beutilized when prior bill information does not contain the desireddenomination. Once the operator indicates that the first no call is a$2, the discriminator would then prompt the operator as to whether thesecond no call was a $50. Since the second no call was indeed a $50 theoperator would choose “ACCEPT”, “YES”, or select the $50 denominationselection element depending on the embodiment chosen. The discriminatorwould then suggest that the third no call was a $10 and the operatorwould similarly indicate acceptance of the $10 suggested denomination.Finally, the discriminator would suggest that the fourth no call was a$10. Since the last no call was a $2, the operator would reject the $10suggestion and indicate that the fourth no call bill was a $2 asdescribed above. The operation of the discriminator using a differentprompting criteria would proceed in a similar manner and as describedabove with respect to each of the described prompting methods.

While discussed above with respect to no calls, the above embodimentscould also be employed in connection with other types of flagged billssuch as reverse-faced bills, reverse forward/reverse oriented bills,unfit bills, suspect bills, etc.

Referring now to FIG. 68, the touch screen I/O device 2956 includes atouch screen 2960 mounted over a graphics display 2961. In oneembodiment, the display 2961 is a liquid crystal display (LCD) withbacklighting. The display may have, for example, 128 vertical pixels and256 horizontal pixels. The display 2961 contains a built-in charactergenerator which permits the display 2961 to display text and numbershaving font and size pre-defined by the manufacturer of the display.Moreover, a controller such as a CPU is programmed to permit the loadingand display of custom fonts and shapes (e.g., key outlines) on thedisplay 2961. The display 2961 is commercially available as Part No.GMF24012EBTW from Stanley Electric Company, Ltd., Equipment ExportSection, of Tokyo, Japan.

The touch screen 2960 may be an X-Y matrix touch screen forming a matrixof touch responsive points. The touch screen 2960 includes two closelyspaced but normally separated layers of optical grade polyester filmeach having a set of parallel transparent conductors. The sets ofconductors in the two spaced polyester sheets are oriented at rightangles to each other so when superimposed they form a grid. Along theoutside edge of each polyester layer is a bus which interconnects theconductors supported on that layer. In this manner, electrical signalsfrom the conductors are transmitted to the controller. When pressurefrom a finger or stylus is applied to the upper polyester layer, the setof conductors mounted to the upper layer is deflected downward intocontact with the set of conductors mounted to the lower polyester layer.The contact between these sets of conductors acts as a mechanicalclosure of a switch element to complete an electrical circuit which isdetected by the controller through the respective buses at the edges ofthe two polyester layers, thereby providing a means for detecting the Xand Y coordinates of the switch closure. A matrix touch screen 2960 ofthe above type is commercially available from Dynapro Thin FilmProducts, Inc. of Milwaukee, Wis.

As illustrated in FIG. 68, the touch screen 2960 forms a matrix ofninety-six optically transparent switch elements having six columns andsixteen rows. The controller is programmed to divide the switch elementsin each column into groups of three to form five switches in eachcolumn. Actuation of any one of the three switch elements forming aswitch actuates the switch. The uppermost switch element in each columnremains on its own and is unused.

Although the touch screen 2960 uses an X-Y matrix of opticallytransparent switches to detect the location of a touch, alternativetypes of touch screens may be substituted for the touch screen 2960.These alternative touch screens use such well-known techniques ascrossed beams of infrared light, acoustic surface waves, capacitancesensing, and resistive membranes to detect the location of a touch. Thestructure and operation of the alternative touch screens are describedand illustrated, for example, in U.S. Pat. Nos. 5,317,140, 5,297,030,5,231,381, 5,198,976, 5,184,115, 5,105,186, 4,931,782, 4,928,094,4,851,616, 4,811,004, 4,806,709, and 4,782,328, which are incorporatedherein by reference.

We claim:
 1. A currency denominating device adapted to receive a stackof currency bills, rapidly denominate and count the bills in the stack,and re-stack the bills comprising: a bill input receptacle adapted toreceive a stack of currency bills; at least one output receptacle; abill transport defining a transport path and adapted to transport thebills, one at a time, from the input receptacle to the output receptaclealong the transport path; a sensor positioned adjacent to the transportpath; a control panel having an input device adapted to receive inputfrom an operator of the device; and a processor electrically coupled tothe sensor and the control panel and programmed to: (a) denominatebills; (b) keep track of the value of bills processed; (c) suspend theoperation of the device when the denominating processor is unable toidentify the denomination of a bill; (d) enable the operator, uponsuspension of the operation of the device, to designate via the controlpanel the denomination of a bill whose denomination is not determined bythe processor; and (e) enable the operator, upon suspension of theoperation of the device, to restart the operation of the device withoutdesignating the denomination of a bill whose denomination is notdetermined by the processor.
 2. The device of claim 1 wherein theprocessor is programmed to restart the operation of the device after theoperator designates the denomination of a bill whose denomination is notdetermined by the processor.
 3. The device of claim 1 wherein theprocessor is programmed to suspend the operation of the device with thebill whose denomination the processor is unable to identify beinglocated in the output receptacle.
 4. A currency denominating devicecomprising: a bill input receptacle; at least one output receptacle; abill transport defining a transport path between the input receptacleand the output receptacle; a sensor positioned adjacent to the transportpath; a control panel having an input device adapted to receive inputfrom an operator of the device; and a processor electrically coupled tothe sensor and the control panel and programmed to: (a) denominatebills; (b) keep track of the value of bills processed; (c) set a flagwhen the denominating processor is unable to identify the denominationof a bill; (d) suspend the operation of the device when the flag is set;(e) enable the operator, upon suspension of the operation of the device,to designate via the control panel the denomination of a bill whosedenomination is not determined by the processor; and (f) enable theoperator, upon suspension of the operation of the device, to restart theoperation of the device without designating the denomination of a billwhose denomination is not determined by the processor.
 5. The device ofclaim 4 wherein the processor is programmed to suspend the operation ofthe device with the bill whose denomination the processor is unable toidentify being located in the output receptacle.
 6. Currencydenominating apparatus comprising: a bill input receptacle; at least oneoutput receptacle; a bill transport adapted to transfer bills betweenthe input receptacle and the output receptacle; one or more sensorspositioned proximate the bill transport and operable to generate signalsindicative of denominational characteristics of bills transported by thetransport; a plurality of denomination keys corresponding to a pluralityof denominations; a continuation key; and a processor programmed to: (a)denominate bills transported by the bill transport in response to thesignals generated by the one or more sensors, (b) keep track of thedenominations of the bills in one or more counters; (c) suspendoperation of the transport when the processor is unable to denominate abill based on the signals; (d) reflect, upon selection of one of thedenomination keys after the operation of the transport has beensuspended, the denomination corresponding to the selected denominationkey in the one or more counters; and (e) restart the operation of thetransport without adversely affecting the one or more counters uponselection of the continuation key after the operation of the transporthas been suspended.
 7. The device of claim 6 wherein the processor isprogrammed to restart the operation of the device upon selection of oneof the denomination keys after the operation of the transport has beensuspended.
 8. Currency denominating apparatus comprising: a bill inputreceptacle adapted to receive a stack of currency bills; at least oneoutput receptacle; a bill transport adapted to transfer bills, one at atime, from the input receptacle to the output receptacle; one or moresensors positioned proximate the bill transport and operable to generatesignals indicative of denominational characteristics of billstransported by the transport; a plurality of denomination keyscorresponding to a plurality of denominations; a continuation key; adenomination counter corresponding to each of the plurality ofdenominations; and a processor programmed to: (a) denominate billstransported by the bill transport in response to the signals generatedby the one or more sensors, (b) keep track of the number of bills ofeach of the plurality of denominations by incrementing the correspondingdenomination counter each time the processor denominates a bill; (c)suspend operation of the transport when the processor is unable todenominate a bill based on the signals with the bill which the processorwas unable to denominate being located at a position where it can beconveniently examined and if desired removed from the device; (d) upon asingle depression of one of the denomination keys after the operation ofthe transport has been suspended, increment the denomination countercorresponding to the denomination of the depressed denomination key andrestart the operation of the transport; and (e) restart the operation ofthe transport without adversely affecting the denomination counters upondepression of the continuation key after the operation of the transporthas been suspended.
 9. Currency denominating apparatus comprising: abill input receptacle adapted to receive a stack of currency bills; atleast one output receptacle; a bill transport adapted to transfer bills,one at a time, from the input receptacle to the output receptacle; oneor more sensors positioned proximate the bill transport and operable togenerate signals indicative of denominational characteristics of billstransported by the transport; a plurality of denomination keyscorresponding to a plurality of denominations; a continuation key; adenomination counter corresponding to each of the plurality ofdenominations; and a processor programmed to: (a) denominate billstransported by the bill transport in response to the signals generatedby the one or more sensors, (b) keep track of the number of bills ofeach of the plurality of denominations by incrementing the correspondingdenomination counter each time the processor denominates a bill; (c)suspend operation of the transport when the processor is unable todenominate a bill based on the signals with the bill which the processorwas unable to denominate being located in the output receptacle where itcan be conveniently examined and if desired removed from the device; (d)upon a single depression of one of the denomination keys after theoperation of the transport has been suspended, increment thedenomination counter corresponding to the denomination of the depresseddenomination key and restart the operation of the transport; and (e)restart the operation of the transport without adversely affecting thedenomination counters upon depression of the continuation key after theoperation of the transport has been suspended.
 10. Currency denominatingapparatus comprising: a bill input receptacle adapted to receive a stackof currency bills; at least one output receptacle; a bill transportadapted to transfer bills, one at a time, from the input receptacle tothe output receptacle; one or more sensors positioned proximate the billtransport and operable to generate signals indicative of denominationalcharacteristics of bills transported by the transport; a plurality ofdenomination keys corresponding to a plurality of denominations; acontinuation key; a denomination counter corresponding to each of theplurality of denominations; and a processor programmed to: (a)denominate bills transported by the bill transport in response to thesignals generated by the one or more sensors, (b) keep track of thenumber of bills of each of the plurality of denominations byincrementing the corresponding denomination counter each time theprocessor denominates a bill; (c) suspend operation of the transportwhen the processor is unable to denominate a bill based on the signalswith the bill which the processor was unable to denominate being locatedas the last bill delivered to the output receptacle where it can beconveniently examined and if desired removed from the device; (d) upon asingle depression of one of the denomination keys after the operation ofthe transport has been suspended, increment the denomination countercorresponding to the denomination of the depressed denomination key andrestart the operation of the transport; and (e) restart the operation ofthe transport without adversely affecting the denomination counters upondepression of the continuation key after the operation of the transporthas been suspended.
 11. A compact, high-speed currency denominatingapparatus comprising: a bill input receptacle adapted to receive a stackof currency bills; a single one output receptacle; a bill transportadapted to transfer bills, one at a time, from the input receptacle tothe output receptacle at rate of at least 1000 bills per minute; one ormore sensors positioned proximate the bill transport and operable togenerate signals indicative of denominational characteristics of billstransported by the transport; a plurality of denomination keyscorresponding to a plurality of denominations; a continuation key; adenomination counter corresponding to each of the plurality ofdenominations; and a processor programmed to: (a) denominate billstransported by the bill transport in response to the signals generatedby the one or more sensors, (b) keep track of the number of bills ofeach of the plurality of denominations by incrementing the correspondingdenomination counter each time the processor denominates a bill; (c)suspend operation of the transport when the processor is unable todenominate a bill based on the signals with the bill which the processorwas unable to denominate being located as the last bill delivered to theoutput receptacle where it can be conveniently examined and if desiredremoved from the device; (d) upon a single depression of one of thedenomination keys after the operation of the transport has beensuspended, increment the denomination counter corresponding to thedenomination of the depressed denomination key and restart the operationof the transport; and (e) restart the operation of the transport withoutadversely affecting the denomination counters upon depression of thecontinuation key after the operation of the transport has beensuspended.
 12. A high-speed currency denominating apparatus comprising:a bill input receptacle adapted to receive a stack of currency bills;exactly two output receptacles; a bill transport adapted to transferbills, one at a time, from the input receptacle to one of the outputreceptacles at rate of at least 1000 bills per minute; one or moresensors positioned proximate the bill transport and operable to generatesignals indicative of denominational characteristics of billstransported by the transport; a plurality of denomination keyscorresponding to a plurality of denominations; a continuation key; adenomination counter corresponding to each of the plurality ofdenominations; and a processor programmed to: (a) denominate billstransported by the bill transport in response to the signals generatedby the one or more sensors, (b) keep track of the number of bills ofeach of the plurality of denominations by incrementing the correspondingdenomination counter each time the processor denominates a bill; (c)suspend operation of the transport when the processor is unable todenominate a bill based on the signals with the bill which the processorwas unable to denominate being located as the last bill delivered to oneof the output receptacles where it can be conveniently examined and ifdesired removed from the device; (d) upon a single depression of one ofthe denomination keys after the operation of the transport has beensuspended, increment the denomination counter corresponding to thedenomination of the depressed denomination key and restart the operationof the transport; and (e) restart the operation of the transport withoutadversely affecting the denomination counters upon depression of thecontinuation key after the operation of the transport has beensuspended.
 13. A currency denominating device comprising: a bill inputreceptacle; at least one output receptacle; a bill transport defining atransport path between the input receptacle and the output receptacle;at least one sensor positioned adjacent to the transport path; a billdenominating processor electrically coupled to the sensor; one or morecounters keeping track of the value of bills processed; a controllerprogrammed to suspend the operation of the device when the denominatingprocessor is unable to identify the denomination of a bill; a pluralityof denomination keys associated with different bill denominations, thedenomination keys enabling the operator to designate the value of a billwhose denomination is not determined by the processor upon suspension ofthe operation of the device; and a continuation key enabling theoperator, upon suspension of the operation of the device, to restart theoperation of the device without designating the value of a bill whosedenomination is not determined by the processor.
 14. The device of claim13 wherein the denomination keys enable the operator to both designatethe value of a bill whose denomination is not determined by theprocessor upon suspension of the operation of the device and restart theoperation of the device with the touch of a single denomination key. 15.A currency counting and discrimination device for receiving a stack ofcurrency bills, rapidly counting and discriminating the bills in thestack, and then re-stacking the bills comprising: an input receptacleadapted to receive a stack of currency bills to be discriminated; adiscriminating unit adapted to discriminate the denomination of thecurrency bills; one or more output receptacles adapted to receive thecurrency bills after being discriminated by the discriminating unit; atransport mechanism adapted to transport the currency bills, one at atime, from the input receptacle past a sensor of the discriminating unitand to the one or more output receptacles; one or more counters adaptedto keep track of the value of bills discriminated; a controllerprogrammed to suspend the operation of the transport mechanism when thediscriminating unit is unable to identify the denomination of a bill;and an operator interface capable of receiving input from an operator ofthe device, the interface enabling, upon suspension of the operation ofthe device, the operator to either (a) indicate the value of a billwhose denomination is not determined by the discriminating unit andrestart the operation of the device or (b) restart the operation of thedevice without indicating the value of a bill whose denomination is notdetermined by the discriminating unit.
 16. The device of claim 15wherein the controller is programmed to suspend the transport mechanismwith the bill whose denomination the discriminating unit is unable toidentify being located in the output receptacle.
 17. A currencydenominating device comprising: an input receptacle; one or more outputreceptacles; a bill transport defining a transport path between theinput receptacle and the one or more output receptacles; a sensorpositioned adjacent to the transport path; a bill denominating processorelectrically coupled to the sensor; one or more counters keeping trackof the value of bills processed; the processor being programmed todenominate bills and flag bills meeting or failing to meet predeterminedcriteria; value indicating means for an operator of said device todesignate the value of any flagged bills, the means appropriatelyaffecting the one or more counters; wherein the predetermined criteriais the denominating processor identifying the denomination of a bill andwherein the processor flags a bill failing to be identified by theprocessor by suspending the operation of the device, the device beinghalted so that the flagged bill is located at an identifiable locationwithin the output receptacle when the bill transport stops.
 18. Anapparatus for processing paper currency having selected denominationswhich comprises: a bill input receptacle; a bill discrimination unitcapable of denominating bills including bills of a plurality ofdenominations; counters operable to count bills of each denominationdenominated by the bill discrimination unit or by the visualdiscrimination; one or more bill output receptacles; a bill transportoperable to transport bills from the input receptacle past the billdiscrimination unit to the bill output receptacles; a plurality ofdenomination keys corresponding to the plurality of denominations; acontinuation key; and a programmable controller operable to actuate andcoordinate operation of the bill transport and the bill discriminationunit, and to suspend operation of the transport in a manner that a billthat the discrimination unit can not denominate is positioned so as toenable visual discrimination of the bill, and to increment anappropriate counter upon selection of one of the denomination keysfollowing suspension of the operation of the transport, and to restartthe operation of the transport without incrementing one of the countersupon selection of the continuation key following suspension of theoperation of the transport.
 19. The apparatus of claim 18 wherein thecontroller is programmed to suspend the transport with the bill whosedenomination the discrimination unit can not denominate being located inthe output receptacle so as to enable its removal prior to selection ofthe continuation key.
 20. A currency denominating device comprising: abill input receptacle; at least one output receptacle; a bill transportdefining a transport path between the input receptacle and the outputreceptacle; a sensor positioned adjacent to the transport path; a billdenominating processor electrically coupled to the sensor; one or morecounters electrically coupled to the processor keeping track of thevalue of bills processed; the processor being programmed to suspend theoperation of the device when the processor is unable to identify thedenomination of a bill; and a control panel enabling the operator todesignate the value of a bill whose denomination is not determined bythe processor, the bill whose denomination is not determined by theprocessor being a no call bill, the control panel alternatively enablingthe operator to restart the operation of the device without designatingthe value of a bill whose denomination is not determined by theprocessor.
 21. The device of claim 20 wherein the processor isprogrammed to suspend the operation of the device with the bill whosedenomination the processor is unable to identify being located in theoutput receptacle so as to enable its removal.
 22. The denominatingdevice of claim 20 wherein the input and output receptacles and the billtransport are contained within a housing and wherein the control panelis affixed to the housing between the input and output receptacles. 23.A currency denominating device comprising: a bill input receptacle; atleast one output receptacle; a bill transport defining a transport pathbetween the input receptacle and the output receptacle; a sensorpositioned adjacent to the transport path; a bill denominating processorelectrically coupled to the sensor; one or more counters keeping trackof the value of bills processed; a flag associated with the processorthat is set when the denominating processor is unable to identify thedenomination of a bill, wherein the operation of the device is suspendedwhen the flag is set; and a control panel having an input device toreceive input from an operator of the device, the control panel enablingthe operator to designate the denomination of a bill whose denominationis not determined by the processor, the bill whose denomination is notdetermined by the processor being a no call bill, the control paneladditionally enabling the operator to restart the operation of thedevice without designating the denomination of a no call bill.
 24. Thedevice of claim 23 wherein the operation of the device is suspended whenthe flag is set with the no call bill being located in the outputreceptacle thereby enabling the operator to remove the no call bill whenthe operation of the device is to be restarted without designating thedenomination of the no call bill.
 25. A currency counting anddiscrimination device for receiving a stack of currency bills, rapidlycounting and discriminating the bills in the stack comprising: an inputreceptacle adapted to receive a stack of currency bills to bediscriminated; a denomination discriminating unit adapted todiscriminate the denomination of the currency bills; one or more outputreceptacles adapted to receive the currency bills after beingdiscriminated by the discriminating unit; a transport mechanism adaptedto transport the currency bills, one at a time, from the inputreceptacle past a sensor of the discriminating unit and to the one ormore output receptacles; and one or more counters adapted to keep trackof the value of bills discriminated; and a plurality of denominationkeys, each key being associated with a given denomination; and acontinuation key; wherein the operation of the device is suspended whenthe discriminating unit is unable to identify the denomination of a billand wherein the selection of one of the plurality of denomination keysappropriately increments the one or more counters based on thedenomination associated with the denomination key that is selected andwherein the selection of the continuation key restarts the operation ofthe device without adding the value of the unidentified bill to the oneor more counters.
 26. The discrimination device of claim 25 wherein theselection of one of the plurality of denomination keys causes theoperation of the device to be resumed.
 27. The discrimination device ofclaim 26 having a single output receptacle.
 28. The device of claim 25wherein the operation of the device is suspended with the unidentifiedbill being located in the output receptacle thereby enabling its removalprior to selection of the continuation key.
 29. A bill counting anddiscrimination device for receiving a stack of bills, rapidly countingand discriminating the bills in the stack, and then re-stacking thebills comprising: an input receptacle adapted to receive a stack ofbills to be discriminated; a denomination discriminating unit adapted todenominate the bills; an output receptacle adapted to receive the billsafter being denominated by the discriminating unit; a transportmechanism adapted to transport the bills, one at a time, from the inputreceptacle past a sensor of the discriminating unit to the outputreceptacle; either (a) one or more denomination counters; each counterkeeping track of the number of denominated bills having to theassociated denomination as determined by the discrimination unit; or (b)a total value counter maintaining the total value of the denominatedbills as they are denominated by the discrimination unit; or (c) bothone or more denomination counters and a total value counter; wherein theoperation of the discrimination device is suspended when thediscriminating unit is unable to identify the denomination of a bill;the operation of the device being stopped so that the unidentified billis the last bill transported to the output receptacle before theoperation of the device is suspended, thereby permitting an operator toconveniently examine the unidentified bill; denomination selectionelements corresponding to one or more denominations whereby selection ofone of the denomination selection elements increases either (i) adenomination counter corresponding to the unidentified bill, (ii) thetotal value counter by the value of the unidentified bill, or (iii) bothand whereby the discrimination device resumes operation; thedenomination selection elements enabling the operator to therebyconveniently increment a respective denomination counter and/or totalvalue counter and to restart the operation of the device when theoperator determines the unidentified bill is acceptable; and acontinuation element the selection of which resumes operation of thediscrimination device without increasing one of the denominationcounters or the total value counter, thereby permitting the operator toremove the unidentified bill from the output receptacle before thediscriminator resumes operation when the operator determines theunidentified bill is not acceptable.
 30. A currency counting anddenominating device for receiving a stack of currency bills, rapidlycounting and denominating the bills in the stack, and then re-stackingthe bills comprising: an input receptacle adapted to receive a stack ofcurrency bills to be discriminated; a discriminating unit adapted todiscriminate the denomination of the currency bills; one or more outputreceptacles adapted to receive the currency bills after beingdenominated by the discriminating unit; a transport mechanism adapted totransport the currency bills, one at a time, from the input receptaclepast a sensor of the discriminating unit and to the one or more outputreceptacles; one or more counters adapted to keep track of the billsdiscriminated; and wherein the operation of the device is suspended whenthe discriminating unit is unable to identify the denomination of abill; denomination keys enabling an operator of the device to designatethe denomination of a bill whose denomination is not determined by thediscriminating unit; and a continuation key enabling an operator of thedevice to restart the device after the operation of the device has beensuspended without adversely affecting the counters.
 31. A currencycounting and discrimination device for receiving a stack of currencybills, rapidly counting and discriminating the bills in the stack, andthen re-stacking the bills comprising: an input receptacle adapted toreceive a stack of currency bills to be discriminated; a discriminatingunit adapted to discriminate the denomination of the currency bills; oneor more output receptacles adapted to receive the currency bills afterbeing discriminated by the discriminating unit; a transport mechanismadapted to transport the currency bills, one at a time, from the inputreceptacle past a sensor of the discriminating unit and to the one ormore output receptacles; and one or more counters keeping track of thebills discriminated; and a plurality of denomination keys, each keybeing associated with a given denomination; and a continuation key;wherein the operation of the device is suspended when the discriminatingunit is unable to identify the denomination of a bill and wherein thedepression of one of the plurality of denomination keys causes thecorresponding denomination to be selected and wherein the depression ofthe continuation key causes the operation of the device to be resumed.32. The device of claim 31 wherein the depression of one of theplurality of denomination keys further causes one or more counters to beappropriately incremented based on the denomination associated with thedenomination key that is selected.
 33. The device of claim 32 whereinthe depression of one of the plurality of denomination keys furthercauses the operation of the device to be resumed.
 34. The device ofclaim 32 wherein the operation of the device is suspended with the billwhose denomination the discriminating unit is unable to identify beinglocated in the output receptacle thereby enabling its removal prior todepression of the continuation key.
 35. The device of claim 31 whereindepression of a key after the depression of one of the denomination keyscauses the denomination associated with the depressed denomination keyto be indicated to the device.
 36. A currency counting anddiscrimination device for receiving a stack of currency bills, rapidlycounting and discriminating the bills in the stack, and then re-stackingthe bills comprising: an input receptacle adapted to receive a stack ofcurrency bills to be discriminated; a discriminating unit adapted todiscriminate the denomination of the currency bills; one or more outputreceptacles adapted to receive the currency bills after beingdiscriminated by the discriminating unit; a transport mechanism adaptedto transport the currency bills, one at a time, from the inputreceptacle past a sensor of the discriminating unit and to the one ormore output receptacles; and one or more counters keeping track of thebills discriminated; and a plurality of denomination keys, each keybeing associated with a given denomination; and one or more additionalkeys; wherein the operation of the device is suspended when thediscriminating unit is unable to identify the denomination of a bill andwherein the depression of one of the plurality of denomination keyscauses the corresponding denomination to be selected and wherein thedepression of one of the additional keys causes the operation of thedevice to be resumed without adversely affecting the one or morecounters.
 37. The device of claim 36 wherein depression of one of theadditional keys after the depression of one of the denomination keyscauses the denomination associated with the depressed denomination keyto be indicated to the device.
 38. The device of claim 36 whereindepression of one of the additional keys after the depression of one ofthe denomination keys causes the one or more counters to beappropriately incremented based on the denomination associated with thedepressed denomination key.
 39. A currency denominating devicecomprising: first means for receiving bills to be denominated; secondmeans for receiving bills after they have been processed; means fortransporting bills from the first means to the second means; means fordenominating bills; means for keeping track of the value of billsprocessed; means for suspending the operation of the device when themeans for denominating bills fails to identify the denomination of abill; means for the operator to input the denomination of a bill whosedenomination is not determined by the means for denominating, the billwhose denomination is not determined by the means for denominating beinga no call bill; and means for the operator to cause the operation of thedevice to be resumed without adversely affecting the means for keepingtrack of the value of the bills.
 40. The device of claim 39 furthercomprising means for appropriately affecting the means for keeping trackof the value of bills in response to the operator inputting thedenomination of a no call bill.
 41. The device of claim 40 furthercomprising means for resuming the operation of the device after theoperator has input the denomination of a no call bill.
 42. A method ofdiscriminating and counting currency bills comprising: receiving a stackof currency bills in an input receptacle of a currency evaluationdevice; transferring the bills, under the control of the evaluationdevice, one at a time from the input receptacle, past a sensor of adiscriminating unit, to an output receptacle; determining, under controlof the evaluation device, the denomination of each passing bill;incrementing, under the control of the evaluation device, a countcorresponding to one of a plurality of denominations based on thedetermined denomination of each passing bill when the device determinesthe denomination of a bill; stopping, under the control of theevaluation device, the transferring when the device is unable todetermine the denomination of a bill so that the bill whose denominationis not determined is located at a predetermined position within theoutput receptacle, the bill whose denomination is not determined beingtermed a no call bill; an operator of the evaluation device examiningthe no call bill; and the operator either (a) depressing a keycorresponding to the denomination of the no call bill when examiningresults in a determination that the bill is acceptable, whereby, underthe control of the discrimination device, the corresponding countassociated with the denomination of the no call bill is incremented andthe transferring is continued; or (b) removing the no call bill withoutreplacement when the examining does not result in a determination thatthe no call bill is acceptable and depressing a continuation keywhereby, under the control of the bill evaluation device, thetransferring is continued.
 43. A method of discriminating and countingcurrency bills comprising: receiving a stack of currency bills in aninput receptacle of a currency denominating device; transferring, underthe control of the device, the bills in the input receptacle one at atime past a denominating sensor to an output receptacle; denominating,under the control of the device, the bills based on a predeterminedcriterion; incrementing, under the control of the device, a countcorresponding to one of a plurality of denominations of bills the deviceis capable of denominating when the device identifies a bill assatisfying the predetermined criterion; stopping, under the control ofthe device, the transferring when a bill fails to satisfy thepredetermined criterion or when the device is unable to determinewhether a bill satisfies the predetermined criterion, the transferringstopping so that the bill that triggered the stopping is located at apredetermined (an identifiable) position within the output receptacle;an operator of the device examining the triggering bill; and theoperator either (a) depressing a key corresponding to the denominationof the triggering bill when the examining results in a determinationthat the bill is acceptable, whereby, under the control of the device,the corresponding count associated with the denomination of thetriggering bill is incremented and the transferring is continued; or (b)removing the triggering bill without replacement when the examining doesnot result in a determination that the triggering bill is acceptable anddepressing a continuation key whereby, under the control of the device,the transferring is continued.
 44. A method of discriminating andcounting currency bills using a currency discriminating device havingdenomination keys and a continuation key and one or more counterskeeping track of bills processed by the device comprising: receiving astack of currency bills in an input receptacle of the currencydiscriminating device; feeding the bills in the input receptacle one ata time past a sensor to one or more output receptacles, generating asignal from the sensor; determining automatically the denomination ofbills fed past the sensor using the signal from the sensor; incrementingan appropriate counter when the denomination of a bill is determinedautomatically; suspending the feeding when the denomination of a bill isnot automatically determined; and either manually designating thedenomination of a bill whose denomination is not automaticallydetermined by depressing an appropriate denomination key or manuallydepressing the continuation key on the device to cause the feeding to beresumed without designating the denomination of a bill whosedenomination is not automatically determined.
 45. The method of claim 44further comprising the discriminating device incrementing an appropriatecounter in response to the depression of the denomination key.
 46. Themethod of claim 45 further comprising the discriminating device resumingoperation in response to the depression of the denomination key.
 47. Themethod of claim 44 wherein the discriminating device has an additionalkey in addition to the denomination keys and further comprising, aftermanually designating the denomination, the discriminating deviceincrementing an appropriate counter in response to the depression of theadditional key.
 48. The method of claim 47 further comprising thediscriminating device resuming operation in response to the depressionof the additional key.
 49. A method of discriminating and countingcurrency bills using a currency discriminating device having keysincluding denomination keys and a continuation key and one or morecounters keeping track of bills processed by the device comprising:receiving a stack of currency bills in an input receptacle of thecurrency discriminating device; feeding the bills in the inputreceptacle one at a time past a sensor of a discriminating unit to oneor more output receptacles, the discriminating unit determining thedenomination of bills fed past the sensor; incrementing an appropriatecounter when the discriminating unit determines the denomination of abill; suspending operation of the device when the discriminating unitfails to determine the denomination of a bill; and either (i) manuallyselecting the denomination of a bill whose denomination is notdetermined by the discriminating unit by depressing an appropriatedenomination key or (ii) manually selecting a continuation key.
 50. Themethod of claim 49 further comprising manually depressing a key afterthe selecting the denomination to cause the selected denomination to beindicated to the device.
 51. A method of discriminating and countingcurrency bills using a currency discriminating device having keysincluding denomination keys and one or more counters keeping track ofbills processed by the device comprising: receiving a stack of currencybills in an input receptacle of the currency discriminating device;feeding the bills in the input receptacle one at a time past a sensor ofa discriminating unit to one or more output receptacles, thediscriminating unit determining the denomination of passing bills;incrementing an appropriate counter when the discriminating unitdetermines the denomination of a bill; suspending operation of thedevice when the discriminating unit fails to determine the denominationof a bill; and either (i) manually selecting an appropriate denominationkey corresponding to the denomination of a bill whose denomination isnot determined by the discriminating unit; (ii) manually selecting acontinuation key.
 52. The method of claim 51 wherein the selecting anappropriate denomination key comprising scrolling to the denomination tobe selected.
 53. The method of claim 52 further comprising the operatormanually selecting a key after the selecting an appropriate denominationkey to cause the selected denomination to be indicated to the device.54. The method of claim 51 further comprising the operator manuallyselecting a key after the selecting an appropriate denomination key tocause the selected denomination to be indicated to the device.
 55. Amethod of discriminating and counting currency bills using a currencydiscriminating device having a control panel and one or more counterskeeping track of bills processed by the device comprising: receiving astack of currency bills in an input receptacle of the currencydiscriminating device; the discriminating device feeding the bills inthe input receptacle one at a time past a sensor of a discriminatingunit to one or more output receptacles, the discriminating unitdetermining the denomination of passing bills; the discriminating deviceincrementing an appropriate counter when the discriminating unitdetermines the denomination of a bill; the discriminating devicesuspending operation when the discriminating unit fails to determine thedenomination of a bill; and an operator of the device either (a) usingthe control panel to manually communicate the denomination of a billwhose denomination is not determined by the discriminating unit to thediscriminating unit or (b) using the control panel to manually restartthe operation of the device without communicating the denomination of abill whose denomination is not determined by the discriminating unit tothe discriminating unit.
 56. The method of claim 55 further comprisingthe discriminating device resuming operation after the operatorcommunicates the denomination of the bill.
 57. A method ofdiscriminating and counting currency bills using a currencydiscriminating device having a control panel and one or more counterskeeping track of bills processed by the device comprising: receiving astack of currency bills in an input receptacle of the currencydiscriminating device; feeding the bills in the input receptacle one ata time past a sensor of a discriminating unit to one or more outputreceptacles, the discriminating unit determining the denomination ofpassing bills; incrementing an appropriate counter when thediscriminating unit determines the denomination of a bill; suspendingthe feeding when the discriminating unit fails to determine thedenomination of a bill with the bill whose denomination thediscriminating unit failed to determine being located in an outputreceptacle; and after suspending the feeding either: (a) manually usingthe control panel to indicate the denomination of the bill whosedenomination is not determined by the discriminating unit or (b)manually removing from the output receptacle the bill whose denominationthe discriminating unit failed to determine and then using the controlpanel to restart the feeding without indicating the denomination of thebill whose denomination is not determined by the discriminating unit.58. The method of claim 57 further comprising resuming feeding the billsafter the denomination of the bill is indicated.